The RAM Torque Rail Base accommodates rails and bars ranging from 1.5" to 2" in diameter - the perfect mounting solution for your ATV or UTV. The include B size hex ball adapter can connect to either side of the Torque base, and is suitable for rugged environments for supporting action cameras, spotlights or other devices. Two sizing inserts - one for attachment to 1.5" rails and the other for attachment to 1.75" rails - are included to create a tight hold while nylon-insert lock nuts prevent loosening in high-vibration environments. Available separately, the RAM B Size Ball Add-On allows you to attach an additional B Size Ball to the Torque Rail Base for mounting multiple devices. This is the "rugged" version as it has an aluminium ball instead of the composite ball on part RAM-B-351-415-15-2U