US Patent 8221041 Fixing device

A fastening arrangement includes a locking part having a head plate and a foot shaft configured with catch noses, bearing tenons, and spring webs having catch noses and web wings. The receiving element includes a profiled surface and an edge wall including inwardly convex portions and outwardly concave portions. When the locking part is in a mounted position, the bearing tenons are disposed in first depressions while the spring webs are in a rear engagement position in which the catch noses engage behind an element. When the locking part is in a demounted position, the bearing tenons are disposed in second depressions and the spring webs are in a released position in which they are out of engagement with the element.