The Raven TopStop upper receiver cover provides complete protection for AR15 and M4 type upper receivers when detached from the lower. This gray polymer cover snaps securely in place to seal the upper receiver and retain internal components during transport or storage.Raven TopStop Upper Receiver Cover - GrayCompatible with most AR15 and M4 type upper receiversTough polymer construction for durabilitySnap-on design for easy installationCompletely seals upper receiver to prevent foulingPrevents bolt carrier group and charging handle from sliding outOnly fits uppers that are detached from the lower receiverEssential for firearm maintenance transport and storage keeping your upper receiver clean and components secure when working on your AR15 or M4 platform rifle.