The RAM-B-224-1, composite twist lock mount consists of a 3.25" rubber base that is connected to the (RAM-B-238), diamond base with 1" rubber ball. The suction cup is designed to have an extra strong hold on any smooth non-porous surface, but for best result, mount the suction cup on a glass or non-porous plastic surface.. Material: High Strength Composite and Marine Grade Aluminium Ball Size: 1" Rubber Ball "B" Size Components RAP-224-1 RAM-B-238