Connect another device to your existing RAM® B- size 1in ball mount with the RAM-B-273U Add-A-Ball Base Adapter. This ball is made up of a 1" or 1.5" ball connecting to a 1/4"-20 threaded stud with a length of 1.6". 

The threads on this ball replace the bolt in the B-size arms, and the ball connects to the middle of the socket arm (not included) on the opposite side of the tightening knob.