This NcStar AR15 Detachable Rear Sight will fit virtually all AR-15, M4, and M16 flattop Picatinny rail upper receivers. The NcStar Detacheable Rear Sight is fully adjustable for elevation and windage by adjustable controls. In addition, is it small enough, youll be able to not only mount a red dot sight but HOLO sights as well.Features: NcStar warranty Made of Hard Anodized AluminumSpecifications: Color: Black Gun Model: AR-15 Fabric/Material: Aluminum & Steel Gun Type: Rifle Length: 2.7 in Weight: 5.1 oz Base/Mount Type: Weaver/Picatinny Gun Page Selector: AR