The RAM-B-259U is designed to mount to the lip edge of a flat surface up to 5/8" thick. Popular mounting edges include a car side window edge lip or glare shield on an airplane. The base has two composite bolts that, when tightened, clamp the base to the lip surface. A RAM 1" diameter rubber ball is connected to the base allowing you to connect a RAM 1" diameter arm socket and connection plates to create the perfect mount for your application.