ROMEO-MSR compact red dot sights provide civilians and armed professionals a robust 1x aiming solution for any situation. Ultra-low parallax so point-of-aim is point-of-impact and the red dot remains parallel to the bore of your firearm"" no matter what your viewing angle is relative to the optical axis of the sight. Unlimited eye-relief allows you to acquire the aiming point and the target regardless of the position of your eye behind the sight. The readily available CR2032 battery is top-loading"" allowing for quick battery replacement (featuring 40""000+ hours or more of life). Dependable waterproof (IPX-7 rated for complete water immersion up to 1 atmosphere) and fog-proof performance.