Two variations of a simplified structure for retaining a device to a mounting surface are appropriate for use with a disconnect block, or for removably retaining any device to a mounting surface. As a disconnect block, cooperating connector portions in mating surfaces of fixed and removable body portions...http://www.google.de/patents/US4527849?utm_source=gb-gplus-sharePatent US4527849 - Snap-in mounting device for electrical devices
