# trigger

> Script interface for the TriggerModule of a Particle System.

## Definition

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

```csharp
public ParticleSystem.TriggerModule trigger { get; }
```

### Remarks

This module is useful for killing particles when they touch a set of collision shapes, or for calling a script command to let you apply custom particle behaviors when the trigger is activated.

The example code for [MonoBehaviour.OnParticleTrigger()](/engine/6000.5/script-reference/unityengine/monobehaviour/onparticletrigger.md) shows how the callback type action works.

Particle System modules do not need to be reassigned back to the system; they are interfaces and not independent objects.