diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 9308e1b..f05b601 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -1,9 +1,11 @@
 name: Build
 
 on:
+  pull_request: 
   push:
     branches:
       - main
+  merge_group:
 
 jobs:
   build:
@@ -27,6 +29,7 @@ jobs:
         run: python src/vbl_aquarium/build.py
       
       - name: 📤 PR changes
+        if: github.ref == 'refs/heads/main'
         uses: peter-evans/create-pull-request@v6
         with:
           token: ${{ secrets.PR_TOKEN }}
diff --git a/src/vbl_aquarium/__about__.py b/src/vbl_aquarium/__about__.py
index a73339b..00ec2dc 100644
--- a/src/vbl_aquarium/__about__.py
+++ b/src/vbl_aquarium/__about__.py
@@ -1 +1 @@
-__version__ = "0.0.8"
+__version__ = "0.0.9"
diff --git a/src/vbl_aquarium/models/unity.py b/src/vbl_aquarium/models/unity.py
index e8d5cb7..d0ed4e1 100644
--- a/src/vbl_aquarium/models/unity.py
+++ b/src/vbl_aquarium/models/unity.py
@@ -27,3 +27,27 @@ class Vector4(BaseModel):
     y: float = 0.0
     z: float = 0.0
     w: float = 0.0
+
+    def __add__(self, other):
+        if isinstance(other, Vector4):
+            return Vector4(x=self.x + other.x, y=self.y + other.y, z=self.z + other.z, w=self.w + other.w)
+        error = f"unsupported operand type(s) for +: 'Vector4' and '{type(other)}'"
+        raise TypeError(error)
+
+    def __sub__(self, other):
+        if isinstance(other, Vector4):
+            return Vector4(x=self.x - other.x, y=self.y - other.y, z=self.z - other.z, w=self.w - other.w)
+        error = f"unsupported operand type(s) for -: 'Vector4' and '{type(other)}'"
+        raise TypeError(error)
+
+    def __mul__(self, other):
+        if isinstance(other, (int, float)):
+            return Vector4(x=self.x * other, y=self.y * other, z=self.z * other, w=self.w * other)
+        error = f"unsupported operand type(s) for *: 'Vector4' and '{type(other)}'"
+        raise TypeError(error)
+
+    def __truediv__(self, other):
+        if isinstance(other, (int, float)):
+            return Vector4(x=self.x / other, y=self.y / other, z=self.z / other, w=self.w / other)
+        error = f"unsupported operand type(s) for /: 'Vector4' and '{type(other)}'"
+        raise TypeError(error)