Anodized aluminum construction. | Superior quality, made of brass, with perfect surface finishing. | This adapter build in the correctional glass, which make the adapter allow focus to infinity. | Smooth surface for effortless mount, fine made to be light weight and strong. Or effortless mount, fine made to be light weight and strong. | Please note: Infinity focus position：the position of the infinity mark 【∞】of the telephoto lens or super telephoto lens is shifted slightly to the positive side to enable focus adjustment even when focus shift is caused due to temperature changes.The shift range is denoted by an L-shaped line, Be sure to check the focus through the viewfinder even when you shoot at infinity.