diff --git a/examples/icetop_book.py b/examples/icetop_book.py
index fcda543..613836d 100755
--- a/examples/icetop_book.py
+++ b/examples/icetop_book.py
@@ -6,7 +6,7 @@
 
 from pathlib import Path
 
-from icecube import icetray, hdfwriter, simclasses
+from icecube import hdfwriter, icetray, simclasses
 
 # The following is an example of some "Level3" files for which S-frames were retrofitted
 # after production.  But the input can be any IceTop simulation files containing S-frames.
diff --git a/examples/nugen_book.py b/examples/nugen_book.py
index 4953596..97f2ed0 100755
--- a/examples/nugen_book.py
+++ b/examples/nugen_book.py
@@ -6,7 +6,7 @@
 
 from pathlib import Path
 
-from icecube import icetray, hdfwriter, simclasses
+from icecube import hdfwriter, icetray, simclasses
 
 FILE_DIR = Path("/data/sim/IceCube/2016/filtered/level2/neutrino-generator/21217/0000000-0000999/")
 files = sorted(str(f) for f in FILE_DIR.glob("Level2_IC86.2016_NuMu.021217.0000*.i3.zst"))
diff --git a/examples/triggered_corsika_book.py b/examples/triggered_corsika_book.py
index f89f12d..9f27f68 100755
--- a/examples/triggered_corsika_book.py
+++ b/examples/triggered_corsika_book.py
@@ -6,7 +6,7 @@
 
 from pathlib import Path
 
-from icecube import icetray, hdfwriter, simclasses
+from icecube import hdfwriter, icetray, simclasses
 
 FILE_DIR = Path("/data/sim/IceCube/2016/filtered/level2/CORSIKA-in-ice/21889/0000000-0000999")
 files = sorted(str(f) for f in FILE_DIR.glob("Level2_IC86.2016_corsika.021889.00000*.i3.zst"))
diff --git a/src/simweights/_fluxes.py b/src/simweights/_fluxes.py
index 437b5df..0a7d333 100644
--- a/src/simweights/_fluxes.py
+++ b/src/simweights/_fluxes.py
@@ -311,22 +311,28 @@ class GlobalFitGST(CosmicRayFlux):
 
 
 class GlobalFitGST_IT(CosmicRayFlux):  # pylint: disable=invalid-name
-    r"""GlobalFitGST for four components [p, He, O, Fe].
+    r"""GlobalFitGST (4 populations) for four components [p, He, O, Fe].
 
-    The Oxygen group is the sum of Nitrogen and Aluminum groups of GlobalFitGST.
+    The Oxygen group is the sum of Carbon and Oxygen groups.
+    The Iron group is the sum of Iron, Tellurium and Mercury groups.
     """
 
     pdgids = PDGID_4COMP
     _funcs = (
-        lambda E: 0.7 * E**-2.66 * exp(-E / 1.2e5) + 0.015 * E**-2.4 * exp(-E / 4e6) + 0.0014 * E**-2.4 * exp(-E / 1.3e9),
-        lambda E: 0.32 * E**-2.58 * exp(-E / 1.2e5 / 2) + 0.0065 * E**-2.3 * exp(-E / 4e6 / 2),
-        lambda E: 0.01 * E**-2.40 * exp(-E / 1.2e5 / 7)
-        + 0.0006 * E**-2.3 * exp(-E / 4e6 / 7)
-        + 0.013 * E**-2.40 * exp(-E / 1.2e5 / 13)
-        + 0.0007 * E**-2.3 * exp(-E / 4e6 / 13),
-        lambda E: 0.006 * E**-2.30 * exp(-E / 1.2e5 / 26)
-        + 0.00023 * E**-2.2 * exp(-E / 4e6 / 26)
-        + 0.0000025 * E**-2.2 * exp(-E / 1.3e9 / 26),
+        lambda E: 0.7000 * E**-2.66 * exp(-E / 1.2e5)
+        + 0.0150 * E**-2.4 * exp(-E / 4e6)
+        + 0.0012 * E**-2.4 * exp(-E / 1.5e9)
+        + 0.00012 * E**-2.4 * exp(-E / 40e9),
+        lambda E: 0.3200 * E**-2.58 * exp(-E / 1.2e5 / 2) + 0.0065 * E**-2.3 * exp(-E / 4e6 / 2),
+        lambda E: 0.0100 * E**-2.40 * exp(-E / 1.2e5 / 6)
+        + 0.0006 * E**-2.3 * exp(-E / 4e6 / 6)
+        + 0.0130 * E**-2.40 * exp(-E / 1.2e5 / 8)
+        + 0.0007 * E**-2.3 * exp(-E / 4e6 / 8),
+        lambda E: 0.0060 * E**-2.30 * exp(-E / 1.2e5 / 26)
+        + 0.00021 * E**-2.2 * exp(-E / 4e6 / 26)
+        + 0.0000011 * E**-2.2 * exp(-E / 1.5e9 / 26)
+        + 0.00001 * E**-2.2 * exp(-E / 4e6 / 52)
+        + 0.000053 * E**-2.2 * exp(-E / 4e6 / 80),
     )