The Lyman™ Receiver Sight 57 SMET-Maus/Spring w/Target Knobs - Sights feature 1/4 minute audible click micrometer windage and elevation adjustments as well as coin-slotted low-profile stayset knobs. The quick-release slide with return-to-zero preset screw allows quick removal and replacement. Includes two interchangeable aperture discs: a large hunting aperture and a small target aperture. Black anodized aluminum body with blue steel knobs and detents.