The RAP-B-101U-LO11 consists of a composite 2.5" diameter round base with the universal AMPS hole pattern, composite B size medium length double socket arm, and adapter base that inserts directly to the back of Lowrance Elite-4, Mark-4, and Hook 4 fish finders. The adapter includes a quick release mechanism, allowing you to remove or transfer your fish finder in seconds. Each 1" rubber ball connects to the composite double socket arm, allowing for near-infinite adjustability and the ideal viewing angle.