1.1. The lens collar is molded in one piece, and avoids the lens switch; the locking knob is not removable; only compatible with Canon 15-35mm F2.8L IS USM; cannot be used with any other lens; 2.2. The inner wall of the lens ring is pasted with PVC film; the installation position is tightly bonded; there should be no stickers at the installation position, if there is, it should be removed, otherwise it will affect the installation; 3.3. When installing, please loosen the knob, align the positions, gently push down, and lock it moderately; The tripod ring cannot be rotated directly on the lens surface; only support horizontal shoot, not support vertical shoot; 4.4. The tripod collar is added 50mm long 39mm Arca fit quick release plate, can be used with 39mm Arca-Swiss fit tripod head and clamp directly; more practical than lens collars without QR-Plate; reserved with 1/4' and 3/8' screw holes and QD hole, and stainless-steel anti-slip screws for fixing lens to tripod directly;