Double Socket Double Socket Arm with Pin-Lock™ Security Knob & Key Knob for 1 inch Balls The RAM-B-201-S consists of a 1 inch 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. They are 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. Dimensions: Overall Length: 3.69 inch Socket-To-Socket Length: 3 inch