Mirror Adaptors. Left hand Yamaha mirrors have a standard clockwise thread, right hand Yamaha mirrors have a reversed anti-clockwise thread. The right hand adaptor in these kits will allow a universal 10mm or 8mm standard thread mirror to be attached. It has a 10mm reverse thread at the base, and an internal 10mm or 8mm standard thread at the top. The left hand adaptor in this kit simply raises the height of the left mirror to match the right hand.