RAM 2.5" Round Base w/ AMPs Hole Pattern & 1.5" Ball
The RAM-202U consists of a 1.5" diameter rubber ball connected to a flat 2.5" diameter base. This mount has pre-drilled holes, including the universal AMPS hole pattern. 
Material: 
Powder Coated Marine Grade Aluminum 
Ball Size: 
1.5" Rubber Ball Size