CRG Expanding Bar End Adapter. Works with CRG bar end mirrors. Machined from 6061-T6 Aluminum CNC Machined Billet Construction. Black Anodized Finish. The 7/8" Adapter kit assembly will work on hollow ended bars with internal diameters as small as 12mm (.475") and as large as 19mm (.750"). This range covers virtually all aluminum and steel bars/clip-ons. Sold Individually.