When you need back-up sights the most, it is best to choose a winner like the Magpul MBUS sights. MBUS sights are easy to activate due to the spring-loaded functionality and include a detent knob for quick windage adjustments. The frame consists of a durable polymer that is both lightweight and ready to take a beating. Included are clamps that allow for the sights to be attached to a MIL-STD-1913 Picatinny/STANAG 4694 receiver rail. When you need a back-up, count on Magpul to be there and ready to roll.