The next evolution in Magpul's MBUS (Magpul Back-Up Sight) line" the MBUS 3 incorporates the best features" strengths and value of their original MBUS and MBUS Pro Sights in a feature-packed back-up sight system. Significantly reduced in size from the MBUS" it sits at just 0.44" high when folded and 1.15" at its widest point. Its aesthetics are derived from the MBUS Pro" but the MBUS 3 Sight is constructed of our impact-resistant polymer" making it lightweight and extremely durable. Featuring the same spring-loaded technology as its predecessor" they can be deployed with an ambidextrous push-button. The MBUS 3 Rear Sight sits at standard AR-height when deployed and includes a rapid-select aperture system.