When you are developing a lightweight, environmentally-friendly vehicle like the Volkswagen up! subcompact, those characteristics have to be considered for every little part, all the way down to things like the ratchet wheel in its seatbelt retractor system. So Key Safety Systems (KSS; keysafetyinc.com) selected a low-emission polyoxymethylene, Hostaform S9364 XAP2 from Ticona (ticona.com) to produce the wheel, as well as the ejector in the belt buckle.
The material features high-level impact toughness and rigidity and can absorb high G-forces while retaining its strength and high-temperature dimensional stability, which are important because degradation due to wear or external influences is to be avoided. Additionally, the material is chemical and scratch resistant.