# callbackLayers

> The Layers that this Collider2D will report collision or trigger callbacks for during a contact with another Collider2D.

## Definition

* **Type:** Property
* **Namespace:** [UnityEngine](/engine/6000.7/script-reference/unityengine.md)
* **Assembly:** UnityEngine.Physics2DModule

```csharp
public LayerMask callbackLayers { get; set; }
```

### Remarks

When a contact occurs between two [Collider2D](/engine/6000.7/script-reference/unityengine/collider2d.md), each [Collider2D](/engine/6000.7/script-reference/unityengine/collider2d.md) will get a collision or trigger callback.  This options allows you to select which layer(s) will produce a callback.

The ability to limit which layers will result in a callback can reduce the complexity of the script inside the callback so that it can safely assume only specific layers will be reported. There is also a performance benefit in not performing callbacks that are not required.

These are all the physics callbacks which are affected by callback layers:

* `OnCollisionEnter2D`

* `OnCollisionStay2D`

* `OnCollisionExit2D`

* `OnTriggerEnter2D`

* `OnTriggerStay2D`

* `OnTriggerExit2D`

**NOTES**:

* This does not control whether the [Collider2D](/engine/6000.7/script-reference/unityengine/collider2d.md) will come into contact or not but simply if the resultant callback will happen.

* Even if all callback layers are selected, only contacts captured via [\_contactCaptureLayers](/engine/6000.7/script-reference/unityengine/collider2d/contactcapturelayers.md), will be reported.

* The other [Collider2D](/engine/6000.7/script-reference/unityengine/collider2d.md) involved in any contact callback disabled here will still receive callbacks defined by its own [callbackLayers](/engine/6000.7/script-reference/unityengine/collider2d/callbacklayers.md) property.

* Normally both the [Collider2D](/engine/6000.7/script-reference/unityengine/collider2d.md) and the [Rigidbody2D](/engine/6000.7/script-reference/unityengine/rigidbody2d.md) it is attached to receive a callback therefore this option controls both those component callbacks.

* When enabling callback layers where callbacks already exist, those contacts will not be reported as new contacts i.e. there will not be an `OnCollisionEnter2D` or `OnTriggerEnter2D` callback produced.

Additional Resources: [LayerMask](/engine/6000.7/script-reference/unityengine/layermask.md)