diff --git a/src/aind_data_schema/core/procedures.py b/src/aind_data_schema/core/procedures.py
index 3ca441e73..251ad4f2d 100644
--- a/src/aind_data_schema/core/procedures.py
+++ b/src/aind_data_schema/core/procedures.py
@@ -19,7 +19,6 @@
     TimeUnit,
     UnitlessUnit,
     VolumeUnit,
-    create_unit_with_value,
 )
 from aind_data_schema_models.brain_atlas import CCFStructure
 from pydantic import Field, SkipValidation, field_serializer, field_validator, model_validator
@@ -202,10 +201,8 @@ class Stain(Reagent):
     """Description of a non-oligo probe stain"""
 
     stain_type: StainType = Field(..., title="Stain type")
-    # TODO: It might be easier to maintain to avoid dynamic model creation
-    concentration: create_unit_with_value("concentration", Decimal, ConcentrationUnit, ConcentrationUnit.UM) = Field(
-        ..., title="Concentration (uM)"
-    )
+    concentration: Decimal = Field(..., title="Concentration")
+    concentration_unit: ConcentrationUnit = Field(default=ConcentrationUnit.UM, title="Concentration unit")
 
 
 class HybridizationChainReaction(AindModel):