---
title: mask
framework: realitykit
role: symbol
role_heading: Instance Property
path: realitykit/collisionfilter/mask
---

# mask

The collision group or groups, stored as a bitmask, with which the entity can collide.

## Declaration

```swift
var mask: CollisionGroup
```

## See Also

### Customizing groups

- [group](realitykit/collisionfilter/group.md)