This Folding Front BUIS (Back-Up Iron Sight) is compatible with MIL-spec height rear AR sights. It locks down, and can be deployed with the push of a button. It's perfect for M4/AR-15 platforms with quick detach optics mounts. • Optimized for AR platform• Compatible with MIL-spec height rear AR sights• Utilizes standard MIL-spec front sight posts and sight adjustment tools• Locks into stowed position with push-button-actuated spring deployment• Aluminum tower body and polymer base for optimal strength-to-weight ratio• Circular hood protects sight post and increases speed acquiring sight picture