diff --git a/api/src/opentrons/protocol_engine/state/modules.py b/api/src/opentrons/protocol_engine/state/modules.py
index 19c03dc7a66..e61d1850c44 100644
--- a/api/src/opentrons/protocol_engine/state/modules.py
+++ b/api/src/opentrons/protocol_engine/state/modules.py
@@ -1314,6 +1314,10 @@ def ensure_and_convert_module_fixture_location(
             # only allowed in column 3
             assert deck_slot.value[-1] == "3"
             return f"absorbanceReaderV1{deck_slot.value}"
+        elif model == ModuleModel.FLEX_STACKER_V1:
+            # only allowed in column 4
+            assert deck_slot.value[-1] == "4"
+            return f"flexStackerV1{deck_slot.value}"
 
         raise ValueError(
             f"Unknown module {model.name} has no addressable areas to provide."
diff --git a/api/src/opentrons/protocol_engine/types.py b/api/src/opentrons/protocol_engine/types.py
index 9d596adbaa8..411b17a0398 100644
--- a/api/src/opentrons/protocol_engine/types.py
+++ b/api/src/opentrons/protocol_engine/types.py
@@ -476,6 +476,7 @@ class ModuleModel(str, Enum):
     HEATER_SHAKER_MODULE_V1 = "heaterShakerModuleV1"
     MAGNETIC_BLOCK_V1 = "magneticBlockV1"
     ABSORBANCE_READER_V1 = "absorbanceReaderV1"
+    FLEX_STACKER_V1 = "flexStackerV1"
 
     def as_type(self) -> ModuleType:
         """Get the ModuleType of this model."""
@@ -491,6 +492,8 @@ def as_type(self) -> ModuleType:
             return ModuleType.MAGNETIC_BLOCK
         elif ModuleModel.is_absorbance_reader(self):
             return ModuleType.ABSORBANCE_READER
+        elif ModuleModel.is_flex_stacker(self):
+            return ModuleType.FLEX_STACKER
 
         assert False, f"Invalid ModuleModel {self}"
 
@@ -533,6 +536,11 @@ def is_absorbance_reader(
     ) -> TypeGuard[AbsorbanceReaderModel]:
         """Whether a given model is an Absorbance Plate Reader."""
         return model == cls.ABSORBANCE_READER_V1
+    
+    @classmethod
+    def is_flex_stacker(cls, model: ModuleModel) -> TypeGuard[FlexStackerModel]:
+        """Whether a given model is a Flex Stacker."""
+        return model == cls.FLEX_STACKER_V1
 
 
 TemperatureModuleModel = Literal[
@@ -547,6 +555,7 @@ def is_absorbance_reader(
 HeaterShakerModuleModel = Literal[ModuleModel.HEATER_SHAKER_MODULE_V1]
 MagneticBlockModel = Literal[ModuleModel.MAGNETIC_BLOCK_V1]
 AbsorbanceReaderModel = Literal[ModuleModel.ABSORBANCE_READER_V1]
+FlexStackerModel = Literal[ModuleModel.FLEX_STACKER_V1]
 
 
 class ModuleDimensions(BaseModel):