The RAM� Torque� handlebar and rail mounting base has a 1� rubber ball and accommodates bars 1 1/8� to 1 1/2� in diameter. Sizing inserts are included to provide a snug fit and protection of the rail. The mount utilizes nylon-insert locknuts to prevent loosening in high vibration environments. Mounting Base Dimensions: Accommodates rails 1 1/8" to 1 1/2" in diameter