# Sandbox.SelectionSystem.Set

```csharp
bool Set(object obj)
```

Clears the selection and sets it to a single object.

### Parameters

- `obj` (`object`): The object to select

### Returns

`bool`: True if the selection changed, false if it was already the only selected object

Declared in [Sandbox.SelectionSystem](/api/Sandbox.SelectionSystem).
Assembly: `Sandbox.System`.