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# mass

The mass of the object attached to the end of the spring.

```
var mass: CGFloat { get set }
```

## Discussion

The default mass is `1`. Increasing this value will increase the spring effect: the attached object will be subject to more oscillations and greater overshoot, resulting in an increased [`settlingDuration`](/documentation/QuartzCore/CASpringAnimation/settlingDuration). Decreasing the mass will reduce the spring effect: there will be fewer oscillations and a reduced overshoot, resulting in a decreased [`settlingDuration`](/documentation/QuartzCore/CASpringAnimation/settlingDuration).

---

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