Available in a 2- or 4-pack system Choose from 7 different colors If you chamber a variety of different AR15 calibers, then you know marking your magazines is much like a home improvement project. (There's usually a lot of paint and tape involved.) But SENTRY knows just how important it is to safely, quickly and efficiently identify ammunition calibers, which is why they pioneered the first-ever colored rifle ammunition identification system - the HexID Color Identification System. Having the peace of mind that your investment, health and safety are all accounted for using the color-coded magazines that can be changed without tools, and in under 1 min, has changed the industry.