diff --git a/src/blenderbim/blenderbim/core/profile.py b/src/blenderbim/blenderbim/core/profile.py
index 58029f1dc4..549120631f 100644
--- a/src/blenderbim/blenderbim/core/profile.py
+++ b/src/blenderbim/blenderbim/core/profile.py
@@ -16,8 +16,20 @@
 # You should have received a copy of the GNU General Public License
 # along with BlenderBIM Add-on.  If not, see <http://www.gnu.org/licenses/>.
 
+from __future__ import annotations
+from typing import TYPE_CHECKING, Optional
 
-def purge_unused_profiles(ifc, profile):
+if TYPE_CHECKING:
+    import bpy
+    import ifcopenshell
+    import blenderbim.tool as tool
+
+
+def purge_unused_profiles(ifc: tool.Ifc, profile: tool.Profile) -> int:
+    """Purge profiles that have no invserses.
+
+    :return: Number of removed profiles.
+    """
     purged_profiles = 0
     for element_profile in profile.get_model_profiles():
         if ifc.get().get_total_inverses(element_profile) > 0:
diff --git a/src/blenderbim/blenderbim/tool/blender.py b/src/blenderbim/blenderbim/tool/blender.py
index 5641f6cf67..6f199abaf4 100644
--- a/src/blenderbim/blenderbim/tool/blender.py
+++ b/src/blenderbim/blenderbim/tool/blender.py
@@ -52,6 +52,17 @@ class Blender(blenderbim.core.tool.Blender):
     OBJECT_TYPES_THAT_SUPPORT_EDIT_GPENCIL_MODE = ("GPENCIL",)
     TYPE_MANAGER_ICON = "LIGHTPROBE_VOLUME" if bpy.app.version >= (4, 1, 0) else "LIGHTPROBE_GRID"
 
+    BLENDER_ENUM_ITEM = Union[tuple[str, str, str], tuple[str, str, str, str], tuple[str, str, str, str, str]]
+    """
+    Options:
+
+    - (identifier, name, description)
+
+    - (identifier, name, description, number)
+
+    - (identifier, name, description, icon, number)
+    """
+
     @classmethod
     def activate_camera(cls, obj: bpy.types.Object) -> None:
 
diff --git a/src/ifcopenshell-python/ifcopenshell/api/material/add_material_set.py b/src/ifcopenshell-python/ifcopenshell/api/material/add_material_set.py
index 7795c73de2..72c090b1ae 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/material/add_material_set.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/material/add_material_set.py
@@ -16,10 +16,19 @@
 # You should have received a copy of the GNU Lesser General Public License
 # along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
 import ifcopenshell
+from typing import Literal
+
+
+MATERIAL_SET_TYPE = Literal[
+    "IfcMaterialLayerSet",
+    "IfcMaterialProfileSet",
+    "IfcMaterialConstituentSet",
+    "IfcMaterialList",
+]
 
 
 def add_material_set(
-    file: ifcopenshell.file, name: str = "Unnamed", set_type: str = "IfcMaterialConstituentSet"
+    file: ifcopenshell.file, name: str = "Unnamed", set_type: MATERIAL_SET_TYPE = "IfcMaterialConstituentSet"
 ) -> ifcopenshell.entity_instance:
     """Adds a new material set
 
@@ -104,7 +113,7 @@ def add_material_set(
         # Great! Let's assign our material set to our wall type.
         ifcopenshell.api.material.assign_material(model, products=[wall_type], material=material_set)
     """
-    settings = {"name": name or "Unnamed", "set_type": set_type or "IfcMaterialConstituentSet"}
+    settings = {"name": name or "Unnamed", "set_type": set_type}
 
     if settings["set_type"] == "IfcMaterialLayerSet":
         return file.create_entity("IfcMaterialLayerSet", LayerSetName=settings["name"] or "Unnamed")