# `GSComponent.componentMasterId`

*Instance Property*

The ID of the base-glyph master to use.

## Declaration

```swift
var componentMasterId: String? { get set }
```

```objc
@property (nonatomic, strong) NSString * componentMasterId;
```

[See also `componentMasterId` in the Python API](https://docu.glyphsapp.com/#GSComponent.componentMasterId)

```python
pyobjc_instanceMethods.componentMasterId() -> str
pyobjc_instanceMethods.setComponentMasterId_(componentMasterId: str)
```

## Discussion

`nil` uses the master associated with the containing layer.

## See Also

### Base Layer

- [`GSComponent componentLayer`](/Core/GlyphsCore/GSComponent/componentLayer) — The applicable layer of the base glyph.
- [`GSComponent preloadCachedLayers`](/Core/GlyphsCore/GSComponent/preloadCachedLayers) — Prepares an interpolated smart-component layer for later access.