RAM 2.25" x 0.87" Motorcycle Base with 11mm Hole and 1" Ball 
The marine grade aluminum base consists of a 1" diameter ball and 2.25" x 0.875" base with 11mm hole. This part is often used on motorcycles, attaching to the mirror frame, the main brand of bike is BMW. This part fits well on many handlebar pinchbolts with a washer (base is 5mm thick).