# Custom

> When the Particle System calculates its velocity, it instead uses the custom value set in ParticleSystem.MainModule.emitterVelocity.

## Definition

* **Type:** Field
* **Namespace:** [UnityEngine](/engine/6000.5/script-reference/unityengine.md)
* **Assembly:** UnityEngine.ParticleSystemModule

```csharp
Custom = 2
```