The Sig Sauer® ROMEO MSR™ is an extremely durable red dot sight optimized for Modern Sporting Rifle platforms, regardless of caliber. This is a parallax-free, 1x20mm sight, with unlimited eye-relief, that delivers rapid target acquisition with both eyes open and head up for maximum situational awareness. The 2 MOA red dot is optimal for close-quarter to mid-range target engagements. Choose from 10 daytime brightness settings, and 2 settings for use with night vision equipment. The sight runs off one CR1632 battery (included) for up to 20,000 hours. Battery is accessible without removing sight from rifle. See-trough, flip-back lens covers protect optics from abrasion, dust and rain. The MSR red dot sight is waterproof rated at IPX-7. The unit comes ready for Picatinny rail interface, with a co-witness 1.41" riser mount.