The RAM-201-SU consists of a 1.5" dia. ball compatible STANDARD LENGTH double socket arm, mixed combination Pin-Lock^™ security nut and key knob. RAM^® Pin-Lock^™ security solutions are designed to withstand the harshest environments where RAM^® Mounts are commonly used. With an emphasis on aesthetics and function, RAM^® security nuts/knobs are low profile and only add a small amount of additional bulk to your system when compared to the standard knob included. At a fraction of the cost of currently available keyed locking knobs, the additional peace of mind and tamper resistance comes at a very affordable price.