RAM Mounts Mirror Mount Base With 1 Ball The marine grade aluminum base Ram-B-252 features a 1 diameter ball and a base measuring 2.25 x 0.875 with an 11mm hole, designed for attachment to the mirror frame. It is well-suited for fitting on numerous handlebar pinchbolts with a washer, thanks to its 5mm thickness. On the other hand, the Ram-B-272 includes a 1 diameter ball and a base with a 9mm hole, also intended for attachment to the mirror frame. It is worth noting that both BMW models commonly utilize either the B-252 or the B-272 for this purpose. Material: Powder Coated Marine Grade Aluminum Ball Size: 1 Rubber Ball B Size