Standard aluminum base with 1 inch diameter B size ball with 1/4-20 inch stud in the baseplate. There are 7 holes in the base; 4 holes in a standard AMPS and 3 holes 120 degrees apart 1/4-20 stud works with standard Camera/Camcorder threaded holes. For use with RAM universal ball and socket mount system. Marine grade aluminum with powder coat finish and rubber balls. Lifetime Warranty.