Ram Double Socket Short Arm with Security Pin-Lock Knob for 1" Ball Bases (sku 30631)Consists of a 1" dia. ball compatible SHORT (1. 75" between centres) 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