---
title: bounds
framework: realitykit
role: symbol
role_heading: Instance Property
path: realitykit/meshinstancescomponent/part/bounds
---

# bounds

The bounding box to encompass all of the instances this group part draws.

## Declaration

```swift
var bounds: BoundingBox?
```

## Discussion

Discussion If bounds is nil, RealityKit calculates a bounding box for you each time you update your instances within LowLevelInstanceData. Automatic bounds calculation is not supported when LowLevelInstanceData is updated via replace(using:). Provide a non-nil bounds value when updating instances with Metal.