diff --git a/source/XeroAPI.Net.nuspec b/source/XeroAPI.Net.nuspec
index 41ef3c5..c648373 100644
--- a/source/XeroAPI.Net.nuspec
+++ b/source/XeroAPI.Net.nuspec
@@ -1,19 +1,18 @@
 <?xml version="1.0"?>
 <package xmlns="http://schemas.microsoft.com/packaging/2010/07/nuspec.xsd">
   <metadata>
-    <id>XeroAPI.Net</id>
-    <version>0.0.0.0</version>
-    <title>.Net wrapper library for Xero API</title>
-    <authors>XeroAPI</authors>
-    <owners />
-    <projectUrl>https://github.com/XeroAPI/XeroAPI.Net</projectUrl>
-    <iconUrl>https://secure.gravatar.com/avatar/7fff030fb8040a5157c3fd463858167f.png?s=128</iconUrl>
+    <id>XeroAPI.Net-4DP</id>
+    <version>1.0.6</version>
+    <title>.Net wrapper library for Xero API with 4DP support</title>
+    <authors>Unleashed Software</authors>
+    <projectUrl>https://github.com/unleashedsoftware/XeroAPI.Net</projectUrl>
     <requireLicenseAcceptance>false</requireLicenseAcceptance>
-    <description>.Net wrapper library for Xero API. This library allows you to perform GET/PUT/POST methods against the Xero API without needing to know the internals of xml serialisation, oauth signatures or character encodings. See http://developer.xero.com for more information.</description>
-    <summary>.Net wrapper library for Xero API</summary>
+    <description>This library is same as XeroAPI.Net (https://www.nuget.org/packages/XeroAPI.Net) with 4DP support by default.</description>
+    <summary>.Net wrapper library for Xero API with 4DP support</summary>
+	<releaseNotes>Replicating fix for bug in Content-Length from https://github.com/XeroAPI/XeroAPI.Net/commit/3946a195397870b81cb5ce55ad9b20dd9c679658</releaseNotes>
   </metadata>
   <files>
-    <file src="XeroApi\bin\Release\XeroApi.dll" target="lib\XeroApi.dll" />
-    <file src="XeroApi\bin\Release\XeroApi.pdb" target="lib\XeroApi.pdb" />
+    <file src="XeroApi\bin\Release\XeroApi.dll" target="lib\net45\XeroApi.dll" />
+    <file src="XeroApi\bin\Release\XeroApi.pdb" target="lib\net45\XeroApi.pdb" />
   </files>
 </package>
\ No newline at end of file
diff --git a/source/XeroApi.Tests/OAuth/Consumer/ConsumerRequestTests.cs b/source/XeroApi.Tests/OAuth/Consumer/ConsumerRequestTests.cs
index fdc4e76..fcc70ab 100644
--- a/source/XeroApi.Tests/OAuth/Consumer/ConsumerRequestTests.cs
+++ b/source/XeroApi.Tests/OAuth/Consumer/ConsumerRequestTests.cs
@@ -53,7 +53,7 @@ public void to_consumer_response_with_current_date_string_should_pass_validation
         [Test]
         public void it_can_parse_unset_IfModifiedSince_date()
         {
-            ConsumerRequest consumerRequest = new ConsumerRequest(null, null, null, null);
+            ConsumerRequest consumerRequest = new ConsumerRequest(null, null, null);
             NameValueCollection headers = new NameValueCollection();
             OAuthContext oauthContext = new OAuthContext {Headers = headers};
 
@@ -126,7 +126,7 @@ public void it_can_read_IfModifiedSince_date_from_oauth_context_property()
 
         private static ConsumerRequest NewConsumerRequest()
         {
-            return new ConsumerRequest(null, null, null, null);
+            return new ConsumerRequest(null, null, null);
         }
 
         private static ConsumerRequest NewConsumerRequest(OAuthContext oAuthContext)
@@ -142,7 +142,7 @@ private static ConsumerRequest NewConsumerRequest(OAuthContext oAuthContext)
                 ConsumerRequestRunner = consumerRequestRunner
             };
 
-            return new ConsumerRequest(oAuthSession, oAuthContext, consumerContext, new NullCertificateFactory());
+            return new ConsumerRequest(oAuthSession, oAuthContext, consumerContext);
         }
     }
 }
diff --git a/source/XeroApi.Tests/XeroApi.Tests.csproj b/source/XeroApi.Tests/XeroApi.Tests.csproj
index c2e8f3e..eca9fea 100644
--- a/source/XeroApi.Tests/XeroApi.Tests.csproj
+++ b/source/XeroApi.Tests/XeroApi.Tests.csproj
@@ -82,4 +82,7 @@
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </None>
   </ItemGroup>
+  <ItemGroup>
+    <Service Include="{82A7F48D-3B50-4B1E-B82E-3ADA8210C358}" />
+  </ItemGroup>
 </Project>
\ No newline at end of file
diff --git a/source/XeroApi.VBTests/XeroApi.VBTests.vbproj b/source/XeroApi.VBTests/XeroApi.VBTests.vbproj
index ac5a326..80f07e9 100644
--- a/source/XeroApi.VBTests/XeroApi.VBTests.vbproj
+++ b/source/XeroApi.VBTests/XeroApi.VBTests.vbproj
@@ -110,6 +110,9 @@
       <Name>XeroApi</Name>
     </ProjectReference>
   </ItemGroup>
+  <ItemGroup>
+    <Service Include="{82A7F48D-3B50-4B1E-B82E-3ADA8210C358}" />
+  </ItemGroup>
   <Import Project="$(MSBuildToolsPath)\Microsoft.VisualBasic.targets" />
   <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
        Other similar extension points exist, see Microsoft.Common.targets.
diff --git a/source/XeroApi/Integration/IntegrationProxy.cs b/source/XeroApi/Integration/IntegrationProxy.cs
index 6fe757a..9926b5d 100644
--- a/source/XeroApi/Integration/IntegrationProxy.cs
+++ b/source/XeroApi/Integration/IntegrationProxy.cs
@@ -12,15 +12,17 @@ namespace XeroApi.Integration
     public class IntegrationProxy : IIntegrationProxy
     {
         private readonly IOAuthSession _oauthSession;
+        private bool _is4DP;
 
 
         /// <summary>
         /// Initializes a new instance of the <see cref="IntegrationProxy"/> class.
         /// </summary>
         /// <param name="oauthSession">The oauth session.</param>
-        public IntegrationProxy (IOAuthSession oauthSession)
+        public IntegrationProxy (IOAuthSession oauthSession, bool is4DP)
         {
             _oauthSession = oauthSession;
+            _is4DP = is4DP;
         }
         
 
@@ -84,7 +86,7 @@ public string UpdateOrCreateElements(string endpointName, string body)
                 ModelTypeHelper.Pluralize(endpointName),
                 null,
                 null,
-                new NameValueCollection { { "summarizeErrors", "false" } }, 
+                GetAdditionalQueryParams(), 
                 null);
 
             if (consumerResponse.IsGoodResponse || consumerResponse.IsClientError)
@@ -105,7 +107,7 @@ public string CreateElements(string endpointName, string body)
                 ModelTypeHelper.Pluralize(endpointName),
                 null,
                 null,
-                new NameValueCollection { { "summarizeErrors", "false" } }, 
+                GetAdditionalQueryParams(),
                 null);
 
             if (consumerResponse.IsGoodResponse || consumerResponse.IsClientError)
@@ -333,5 +335,15 @@ public static Uri ConstructChildResourceUri(Uri baseUrl, string endpointName, st
             return uriBuilder.Uri;
         }
         
+
+        private NameValueCollection GetAdditionalQueryParams()
+        {
+            var additionalQueryParams = new NameValueCollection { { "summarizeErrors", "false" } };
+            if (_is4DP)
+            {
+                additionalQueryParams.Add("unitdp", "4");
+            }
+            return additionalQueryParams;
+        }        
     }
 }
diff --git a/source/XeroApi/Model/Contact.cs b/source/XeroApi/Model/Contact.cs
index 8f70750..ddc369d 100644
--- a/source/XeroApi/Model/Contact.cs
+++ b/source/XeroApi/Model/Contact.cs
@@ -6,7 +6,7 @@ public class Contact : EndpointModelBase
     {
         [ItemId]
         public Guid ContactID { get; set; }
-        
+
         [ItemNumber]
         public string ContactNumber { get; set; }
 
@@ -14,40 +14,40 @@ public class Contact : EndpointModelBase
         public DateTime? UpdatedDateUTC { get; set; }
 
         public string ContactStatus { get; set; }
-        
+
         public string Name { get; set; }
 
         public string FirstName { get; set; }
 
         public string LastName { get; set; }
-        
+
         public string EmailAddress { get; set; }
-        
+
         public string SkypeUserName { get; set; }
 
         public ContactPersons ContactPersons { get; set; }
-        
+
         public string BankAccountDetails { get; set; }
-        
+
         public string TaxNumber { get; set; }
-        
+
         public string AccountsReceivableTaxType { get; set; }
-        
+
         public string AccountsPayableTaxType { get; set; }
-        
+
         public Addresses Addresses { get; set; }
-        
+
         public Phones Phones { get; set; }
-        
+
         public ContactGroups ContactGroups { get; set; }
-        
+
         [ReadOnly]
         public bool IsSupplier { get; set; }
 
         [ReadOnly]
         public bool IsCustomer { get; set; }
-        
-        public string DefaultCurrency { get;  set; }
+
+        public string DefaultCurrency { get; set; }
 
         public Balances Balances { get; set; }
 
@@ -55,6 +55,8 @@ public class Contact : EndpointModelBase
 
         public PaymentTerms PaymentTerms { get; set; }
 
+        public string AccountNumber { get; set; }
+
         public override string ToString()
         {
             return string.Format("Contact:{0}", Name);
@@ -64,5 +66,5 @@ public override string ToString()
     public class Contacts : ModelList<Contact>
     {
     }
-    
+
 }
\ No newline at end of file
diff --git a/source/XeroApi/OAuth/Consumer/ConsumerRequest.cs b/source/XeroApi/OAuth/Consumer/ConsumerRequest.cs
index f4736e7..9a3d3fb 100644
--- a/source/XeroApi/OAuth/Consumer/ConsumerRequest.cs
+++ b/source/XeroApi/OAuth/Consumer/ConsumerRequest.cs
@@ -39,16 +39,13 @@ public class ConsumerRequest : IConsumerRequest
     {
         private readonly IOAuthConsumerContext _consumerContext;
         private readonly IOAuthContext _context;
-        private readonly ICertificateFactory _clientSslCertificateFactory;
         private readonly IOAuthSession _oauthSession;
 
-        public ConsumerRequest(IOAuthSession oauthSession, IOAuthContext context, IOAuthConsumerContext consumerContext,
-                               ICertificateFactory clientSslCertificateFactory)
+        public ConsumerRequest(IOAuthSession oauthSession, IOAuthContext context, IOAuthConsumerContext consumerContext)
         {
             _oauthSession = oauthSession;
             _context = context;
             _consumerContext = consumerContext;
-            _clientSslCertificateFactory = clientSslCertificateFactory;
         }
 
         public IOAuthContext Context
@@ -65,8 +62,8 @@ public virtual HttpWebRequest ToWebRequest()
         {
             RequestDescription description = GetRequestDescription();
 
-            var request = (HttpWebRequest) WebRequest.Create(description.Url);
-            request.Timeout = (int) TimeSpan.FromMinutes(3).TotalMilliseconds; 
+            var request = (HttpWebRequest)WebRequest.Create(description.Url);
+            request.Timeout = (int)TimeSpan.FromMinutes(3).TotalMilliseconds;
             request.Method = description.Method;
             request.UserAgent = _consumerContext.UserAgent;
 
@@ -116,18 +113,6 @@ public virtual HttpWebRequest ToWebRequest()
                     request.Headers[key] = description.Headers[key];
                 }
             }
-
-            // Attach a client ssl certificate to the HttpWebRequest
-            if (_clientSslCertificateFactory != null)
-            {
-                X509Certificate2 certificate = _clientSslCertificateFactory.CreateCertificate();
-
-                if (certificate != null)
-                {
-                    request.ClientCertificates.Add(certificate);
-                }
-            }
-
             return request;
         }
 
@@ -138,13 +123,14 @@ public RequestDescription GetRequestDescription()
                 _consumerContext.SignContext(_context);
             }
 
+
             Uri uri = _context.GenerateUri();
 
             var description = new RequestDescription
-                                  {
-                                      Url = uri,
-                                      Method = _context.RequestMethod
-                                  };
+            {
+                Url = uri,
+                Method = _context.RequestMethod
+            };
 
             if ((_context.FormEncodedParameters != null) && (_context.FormEncodedParameters.Count > 0))
             {
@@ -175,7 +161,7 @@ public HttpWebResponse ToWebResponse()
             try
             {
                 HttpWebRequest request = ToWebRequest();
-                return (HttpWebResponse) request.GetResponse();
+                return (HttpWebResponse)request.GetResponse();
             }
             catch (WebException webEx)
             {
@@ -240,7 +226,7 @@ private void EnsureRequestHasNotBeenSignedYet()
                 AssertValidIfModifiedSinceDate(context.IfModifiedSince.Value);
                 return context.IfModifiedSince.Value;
             }
-            
+
             string ifModifiedSinceString = context.Headers["If-Modified-Since"];
 
             if (string.IsNullOrEmpty(ifModifiedSinceString))
@@ -253,7 +239,7 @@ private void EnsureRequestHasNotBeenSignedYet()
                 AssertValidIfModifiedSinceDate(ifModifiedSinceDate);
                 return ifModifiedSinceDate;
             }
-            
+
             return null;
         }
 
diff --git a/source/XeroApi/OAuth/Consumer/ConsumerResponse.cs b/source/XeroApi/OAuth/Consumer/ConsumerResponse.cs
index 58e13c7..801e5ee 100644
--- a/source/XeroApi/OAuth/Consumer/ConsumerResponse.cs
+++ b/source/XeroApi/OAuth/Consumer/ConsumerResponse.cs
@@ -57,7 +57,7 @@ public class ConsumerResponse : IConsumerResponse
             if (webResponse.Headers["Content-Type"] != string.Empty)
                 ContentType = webResponse.Headers["Content-Type"];
 
-            if (webResponse.Headers["Content-Length"] != string.Empty)
+            if (!string.IsNullOrEmpty(webResponse.Headers["Content-Length"]))
                 ContentLength = int.Parse(webResponse.Headers["Content-Length"]);
 
             TimeTaken = timeTaken;
diff --git a/source/XeroApi/OAuth/Consumer/DefaultConsumerRequestFactory.cs b/source/XeroApi/OAuth/Consumer/DefaultConsumerRequestFactory.cs
index b53ee51..acda6e7 100644
--- a/source/XeroApi/OAuth/Consumer/DefaultConsumerRequestFactory.cs
+++ b/source/XeroApi/OAuth/Consumer/DefaultConsumerRequestFactory.cs
@@ -10,10 +10,6 @@ public DefaultConsumerRequestFactory()
         {
         }
 
-        public DefaultConsumerRequestFactory(ICertificateFactory clientSslCertificateFactory)
-        {
-            CertificateFactory = clientSslCertificateFactory;
-        }
 
         public static IConsumerRequestFactory Instance
         {
@@ -21,15 +17,10 @@ public static IConsumerRequestFactory Instance
             set { _defaultInstance = value; }
         }
 
-        public ICertificateFactory CertificateFactory
-        {
-            get; 
-            set;
-        }
 
         public IConsumerRequest CreateConsumerRequest(IOAuthSession session, IOAuthContext context, IOAuthConsumerContext consumerContext)
         {
-            return new ConsumerRequest(session, context, consumerContext, CertificateFactory);
+            return new ConsumerRequest(session, context, consumerContext);
         }
     }
 }
\ No newline at end of file
diff --git a/source/XeroApi/OAuth/Framework/DateTimeUtility.cs b/source/XeroApi/OAuth/Framework/DateTimeUtility.cs
index 6922d5c..1164107 100644
Binary files a/source/XeroApi/OAuth/Framework/DateTimeUtility.cs and b/source/XeroApi/OAuth/Framework/DateTimeUtility.cs differ
diff --git a/source/XeroApi/OAuth/Framework/NonceGenerator.cs b/source/XeroApi/OAuth/Framework/NonceGenerator.cs
index 0acec50..905806b 100644
Binary files a/source/XeroApi/OAuth/Framework/NonceGenerator.cs and b/source/XeroApi/OAuth/Framework/NonceGenerator.cs differ
diff --git a/source/XeroApi/OAuth/XeroApiEndpoints.cs b/source/XeroApi/OAuth/XeroApiEndpoints.cs
index 0455354..4ea62c0 100644
--- a/source/XeroApi/OAuth/XeroApiEndpoints.cs
+++ b/source/XeroApi/OAuth/XeroApiEndpoints.cs
@@ -5,15 +5,15 @@ namespace XeroApi.OAuth
     public class XeroApiEndpoints
     {
         public static Uri PublicRequestTokenUri = new Uri("https://api.xero.com/oauth/RequestToken");
-        public static Uri PartnerRequestTokenUri = new Uri("https://api-partner.network.xero.com/oauth/RequestToken");
+        public static Uri PartnerRequestTokenUri = new Uri("https://api.xero.com/oauth/RequestToken");
 
         public static Uri UserAuthorizeUri = new Uri("https://api.xero.com/oauth/Authorize");
 
         public static Uri PublicAccessTokenUri = new Uri("https://api.xero.com/oauth/AccessToken");
-        public static Uri PartnerAccessTokenUri = new Uri("https://api-partner.network.xero.com/oauth/AccessToken");
+        public static Uri PartnerAccessTokenUri = new Uri("https://api.xero.com/oauth/AccessToken");
 
         public static Uri PublicBaseEndpointUri = new Uri("https://api.xero.com/api.xro/2.0/");
-        public static Uri PartnerBaseEndpointUri = new Uri("https://api-partner.network.xero.com/api.xro/2.0/");
+        public static Uri PartnerBaseEndpointUri = new Uri("https://api.xero.com/api.xro/2.0/");
     }
     
 }
diff --git a/source/XeroApi/OAuth/XeroApiPartnerSession.cs b/source/XeroApi/OAuth/XeroApiPartnerSession.cs
index 280c45b..da0ca9e 100644
--- a/source/XeroApi/OAuth/XeroApiPartnerSession.cs
+++ b/source/XeroApi/OAuth/XeroApiPartnerSession.cs
@@ -9,17 +9,17 @@ namespace XeroApi.OAuth
     public class XeroApiPartnerSession : OAuthSession
     {
         [Obsolete("Use the constructor with ITokenRepository")]
-        public XeroApiPartnerSession(string userAgent, string consumerKey, X509Certificate2 signingCertificate, X509Certificate2 sslCertificate)
+        public XeroApiPartnerSession(string userAgent, string consumerKey, X509Certificate2 signingCertificate)
             : base(CreateConsumerContext(userAgent, consumerKey, signingCertificate))
         {
-            ConsumerRequestFactory = new DefaultConsumerRequestFactory(new SimpleCertificateFactory(sslCertificate));
+            ConsumerRequestFactory = new DefaultConsumerRequestFactory();
         }
 
 
-        public XeroApiPartnerSession(string userAgent, string consumerKey, X509Certificate2 signingCertificate, X509Certificate2 sslCertificate, ITokenRepository tokenRepository)
+        public XeroApiPartnerSession(string userAgent, string consumerKey, X509Certificate2 signingCertificate, ITokenRepository tokenRepository)
             : base(CreateConsumerContext(userAgent, consumerKey, signingCertificate), tokenRepository)
         {
-            ConsumerRequestFactory = new DefaultConsumerRequestFactory(new SimpleCertificateFactory(sslCertificate));
+            ConsumerRequestFactory = new DefaultConsumerRequestFactory();
         }
 
 
diff --git a/source/XeroApi/Repository.cs b/source/XeroApi/Repository.cs
index 3cd9642..7901078 100644
--- a/source/XeroApi/Repository.cs
+++ b/source/XeroApi/Repository.cs
@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Linq;
 
@@ -20,9 +20,9 @@ public class Repository : IRepository
         /// Initializes a new instance of the <see cref="Repository"/> class.
         /// </summary>
         /// <param name="oauthSession">The oauth session.</param>
-        public Repository(IOAuthSession oauthSession)
+        public Repository(IOAuthSession oauthSession, bool is4DP = true)
         {
-            _proxy = (new IntegrationProxy(oauthSession));
+            _proxy = (new IntegrationProxy(oauthSession, is4DP));
             _provider = new ApiQueryProvider(_proxy);
         }