diff --git a/systematics/reint/README b/systematics/reint/README
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+Input files for Geant4Reweight systematics.
+
+These files are specific to the Geant4 models, and must match those used in
+the simulation. To generated new ROOT files, see the Geant4Reweight
+documentation for usage of the G4CrossSection and G4Cascade utilities.
+
diff --git a/systematics/reint/g4_cross_section_piminus.root b/systematics/reint/g4_cross_section_piminus.root
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diff --git a/systematics/reint/g4_fracs_piminus.root b/systematics/reint/g4_fracs_piminus.root
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diff --git a/systematics/reint/g4_fracs_proton.root b/systematics/reint/g4_fracs_proton.root
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