Magpul MAG1167-BLK MBUS 3 Rear Flip-Up Black SightMagpul takes their back up sight to the next level with the MBUS (Magpul Back Up Sight) 3. The weight has been reduced to a mere 30 grams and sits at just 0.55 high when folded and measures 1.38 at its widest point. Just like its predecessor the MBUS 3 utilizes a spring-loaded operation, allowing them to be deployed instantly and accommodates left and right-handed users. Once mounted, the MBUS 3 sits at standard AR height when deployed, and windage/elevation adjustments can be made without the use of tools. Available in both front and rear sight configurations. FeaturesLightweight & Durable Polymer ConstructionSpring Loaded OperationAmbidextrousMounts via 1913 Picatinny Rail Magpul MBUS-3 Flip-Up Polymer Rear Sight for Picatinny Rail, Black MAG1167-BLK