Which component is NOT typically found on a traditional Pilates reformer?

The arc is not typically a component found on a traditional Pilates reformer. Traditional Pilates reformers are designed with several specific components that facilitate various exercises. The foot-bar serves as a point of contact for the feet or hands during movements, allowing practitioners to push or pull against it. The sliding carriage is a key feature that moves along a set of rails, enabling a wide range of exercises that focus on resistance and body alignment. Resistance springs are also essential, as they provide the necessary tension for exercises, allowing for adjustments in strength and support.

The arc, while it may be a part of some Pilates equipment or used in certain exercises, is not standard on the traditional reformer. It’s important to note that the reformer's design focuses on providing a stable platform with adjustable resistance, rather than additional components that are not essential to its primary functions.