These Zeiss Ultralight 1913 Mil-Spec Precision Rings are manufactured to the highest of standards, from premium materials, and with tight tolerances for your long-term safety and field applications. An integral anti-cant bubble level is located on the top half of the rugged 7075-T6 aluminum rings to check if you are level while shooting. Mount these 36mm high rings on a high-quality 1913 Mil-Std rail to obtain the best results. A hard case with both T15 and T25 Torx driver bits is included.