# mask

> Category mask used to filter which attached shapes contribute. A shape participates iff (shape.contactFilter.categories.bitMask & mask.bitMask)!= 0. Defaults to PhysicsMask.All when the input is created via the parameterless constructor.

## Definition

* **Type:** Property
* **Namespace:** [Unity.U2D.Physics](/engine/6000.6/script-reference/unity/u2d/physics.md)
* **Assembly:** UnityEngine.PhysicsCore2DModule

```csharp
public PhysicsMask mask { readonly get; set; }
```