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

# mask

The set of collision groups, stored as a bit mask, towards which the entity introduces one-way collisions.

## Declaration

```swift
var mask: ClothCollisionGroupSet
```

## See Also

### Configuring collision groups

- [groups](realitykit/clothcollisionfilter/groups.md)