# One

> Bit #0 set (1) in the PhysicsMask. The remaining bits are reset (0).

## Definition

* **Type:** Field
* **Namespace:** [UnityEngine.LowLevelPhysics2D](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d.md)
* **Assembly:** UnityEngine.Physics2DModule

```csharp
public static readonly PhysicsMask One
```