Consists of a 1" diameter (B) size rubber mounting ball and a 2.25" x .875" base with an 11mm hole This part is often used on motorcycles, attaching to the mirror frame - main brand of bike for the RAM-B-252U is BMW Fits well on many handlebar pinchbolts with a washer (base is 5mm thick) Made of powder coated marine grade aluminum Display packaged For more information on this product check out this video.