Meprolight M21 Polarizer and Flash Guard Kit for M21 Sights M21 PFK. These Red Dot Sight Accessories crafted by Meprolight sharpen your aiming point to allow more precise and quicker target acquisition under a wider range of lighting conditions. You may be asking how this device can upgrade your current optic. Well it acts as a polarizing filter - organizing light waves in a manner that creates a more vivid image while looking down your sights. Additionally the Meprolight Polarize + Flash Guard Kit protects the lens from getting scratched to preserve the quality of your sight. Reducing glare and clarifying your sight makes a massive difference in your overall accuracy and shooting experience. Boost the potential of your firearm and optic with the Meprolight M21 Aim Enhancer. Specifications for Meprolight M21 Polarizer Kit: Manufacturer: Meprolight Color: Black Condition: New Package Contents: Meprolight M21 Polarizer Kit Meprolight 5626090000: M21 Polarizer and Flash Guard Kit for M21 Sights M21 PFK