Building on the proven MBUS Pro platform, the MBUS Pro Offset Sights are part of an an effective aiming system to supplement magnified optics on M1913 Picatinny mounting surfaces. In the event of a damaged or nonfunctional primary optic, or a close target, rotating the rifle 45 degrees provides the shooter with a fully-featured iron sighting solution. The MBUS Pro Offset Rear Sight features durable Melonited steel construction, positive detented lockup when deployed, tool-less windage adjustment for easy zeroing, dual rear apertures, and a low profile footprint to ensure compatibility and reduce interference with most rifle setups. Only compatible with MBUS Pro OFFSET Front sight MAG525. Small aperture diameter 0.07 in. Large aperture diameter 0.19 in. 0.5 MOA (0.566"/100m) per click with a 14.5" sight radius. 0.4 MOA (0.410"/100m) per click with a 20" sight radius. Made in the USA.