RAM WITH 2 U BOLTS WITH 1.5 BALL FOR 1 1.2 DIA RAM Double U Bolt Mount with Double Ball Adapter RAM Mount 1.5" C Size Ball with Double U Bolt Handlebar Rail Base RAM C Size 1.5" Ball Rail Mount with Double U Bolt Base & 2.5" Round. RAM DOUBLE U BOLT MOUNT 1. 5" BALL for rails 19mm to 31mm OD. RAM 235 The RAM 235, double u bolt mount, will fit rails between 19mm to 31mm in diameter. Including a 1. 5" rubber ball for extra holding support, the base connects to the rail with two stainless steel u bolts. Manufactured from Powder Coated Marine Grade Aluminium and Stainless Steel.