The RAP-224-1U, suction cup twist lock base, contains a standard RAM double hole diamond shaped end. The 3.3" diameter 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 surface. The diamond shaped end has two holes 1.912" from center to center. This will connect to RAM-B-238 Diamond Plates Series, the universal industry standard AMPS hole pattern or directly to the back of the RAM Composite HOL Cradles. This suction base DOES NOT have a RAM 1" rubber connection ball.