The TopStop cover is expertly designed to fit most AR-15 and M4-type upper receivers when they are detached from the lower receiver, providing essential protection for your firearm. This cover securely seals the upper receiver, preventing fouling, dirt, and debris from contaminating the internal components. Additionally, it ensures that the bolt carrier group and charging handle remain firmly in place, even during movement or handling. By keeping your upper receiver protected and secure, the TopStop cover enhances the longevity and reliability of your firearm, making it an indispensable accessory for every serious shooter. Designed to snap-on most AR-15 or M4-type upper receivers, offering easy and secure installation for a wide range of AR-based platforms This will only fit uppers that are detached from the lower, ensuring compatibility with specific firearm configurations It features tough polymer construction