The RAM-201U consists of a medium length double socket arm that accommodates 1.5" C size ball bases, device holders, and adapters. A single spring inside the arm keeps the socket open, and allows you to insert the ball into the socket connection. This arm has an overall length of 5.69". The easy to adjust knob allows for near-infinite adjustability. This arm has a 4lb weight capacity. It is made of powder-coated, marine-grade aluminum for durability and reliability in the most demanding environments and backed by a lifetime warrenty.