Contact Ring
WARNING: This page is about a different car, the 2001 BMW M5, 2001 BMW 540i, 2001 BMW 530i, and 2001 BMW 525i. However, it is still accessible from the selected car via links, so may be relevant.
Contact ring (mounted on bottom of steering wheel) is a continuous loop of wire ribbon that forms an electrical circuit between the steering wheel and steering column. This wire ribbon winds and unwinds to ensure electrical contact when the steering wheel is turned.