This NcStar AR15 Flip Up Rear Sight will fit virtually all AR-15, M4, and M16 flattop Picatinny rail upper receivers. The NcStar Flip Up Rear Sight is fully adjustable for elevation and windage by adjustable controls. In addition, is it small enough, you'll be able to not only mount a red dot sight but HOLO sights as well. We offer complete line of NcStar Shooting Accessories.Features:NcStar warrantyMade of Hard Anodized AluminumSpecifications:Gun Model: AR-15Gun Page Selector: AR