RAM Mount RAM Rail Clamp Ball Base for 2" - 2.5" Rails [RAM-271U-2]RAM Rail Clamp Ball Base for 2" 2. 5" Rails The RAM 271U 2, round pipe base, consists of a 1. 5" rubber ball connected that will connect to a pipe tubing diameter from 2" to 2. 5" in diameter. Hardware: (4) 1 4" 20 x 1. 5" Screws (4) 1 4" 20 Nylock Nuts (4) Rubber Caps Specifications: Clamp Range: 2" 2. 25" diameter Ball Socket Size: C Size (1. 5") Materials: Marine grade aluminum