The RAM-201-SU consists of a 1.5" dia. ball compatible STANDARD LENGTH double socket arm, mixed combination Pin-Lock&trade   security nut and key knob. 

RAM®   Pin-Lock&trade   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. 

Dimensions:  
Overall Length: 5.625"
Socket-To-Socket Length: 4.5" 

Material: 
Powder Coated Marine Grade Aluminum

Ball Size: 
1.5" Rubber Ball Size 

Note: 
The "U" in the part number reflects product packaged in poly bag.