# prepareMaterialPropertyBlockCallback

> The optional callback to prepare the material property block for the effect.

## Definition

* **Type:** Property
* **Namespace:** [UnityEngine.UIElements](/engine/6000.3/script-reference/unityengine/uielements.md)
* **Assembly:** UnityEngine.UIElementsModule

> **Warning:**
>
> **Deprecated.** This property will be removed. Use applySettingsCallback instead, which provides additional contextual information.

```csharp
public PostProcessingPass.PrepareMaterialPropertyBlockDelegate prepareMaterialPropertyBlockCallback { readonly get; set; }
```