ZEISS Ultralight 1913 Mil-Spec Rings are manufactured to the highest of standards, from premium materials, and with tight tolerances for your long-term safety and field applications. They are designed for optimal long-range shooting solutions and allow for either right- or left-handed operations as well as eye dominance. The bubble level is easily viewed from the shooting position, creating no disturbance in your shooting position. A smarter, sleeker, and ultralightweight ring design for all heavy-duty hunting and shooting applications. Integral anti-cant bubble level in top half of ring Type 303 stainless steel top cap screws - with black oxide finish Micro-radiused on all machined leading edges to ensure a non-marring design Hard case included, with both T15 and T25 Torx driver bits Integral bottom recoil lug for best alignment and a secure zero under the harshest recoil Approximately 4.41 oz. with screws (pair 30mm low) 7075-T6 aluminum, Mil-Spec, Type III, 30-micron hard anodized finish - matte black NOTE : For optimum performance and flawless mounting, ZEISS strongly advises that you mount the precision rings on a high-quality 1913 Mil-Std specification rail to obtain best results.