diff --git a/src/config/constants.js b/src/config/constants.js
index 304a435..8e66871 100644
--- a/src/config/constants.js
+++ b/src/config/constants.js
@@ -51,6 +51,8 @@ const CustomAttributeTypes = [
   "Enumerable",
 ];
 
+const SublevelInventoryTypes = ["Inventory", "Material", "Item"];
+
 const AUTHENTICATION_FAILURE_ERROR_MESSAGE = "Authentication Failed!";
 const AUTHORIZATION_FAILURE_ERROR_MESSAGE =
   "User not permitted due to lack of access!";
@@ -63,6 +65,7 @@ module.exports = {
   WarehouseScopes,
   InventoryTypes,
   CustomAttributeTypes,
+  SublevelInventoryTypes,
   SubLevelTypes,
   LevelPositions,
   SUPER_ADMIN_ROLE: "super-admin",
diff --git a/src/models/Sublevel.js b/src/models/Sublevel.js
index 9873d87..5da8c61 100644
--- a/src/models/Sublevel.js
+++ b/src/models/Sublevel.js
@@ -1,5 +1,5 @@
 const mongoose = require("mongoose");
-const { SubLevelTypes, LevelPositions } = require("../config/constants");
+const { SubLevelTypes, LevelPositions, SublevelInventoryTypes } = require("../config/constants");
 
 const schema = new mongoose.Schema(
   {
@@ -57,10 +57,16 @@ const schema = new mongoose.Schema(
       default: false,
     },
     preffered_inventory: [
-      // {
-      //   type: mongoose.Schema.Types.ObjectId,
-      //   ref: "Inventory",
-      // },
+      {
+        id: {
+          type: mongoose.Schema.Types.ObjectId,
+          refPath: "type",
+        },
+        type: {
+          type: String,
+          enum: SublevelInventoryTypes,
+        },
+      },
     ],
   },
   {