The ranger plates are a baseplate upgrade for PMAG M3 7.62x51 magazines (AR-10 LR/SR format).
Getting your fingers into the loop allows easy gripping of magazines when whipping them out from pouches, holders or loops.
Plus, made from a slightly rubbery flexible material they protect mag and rifle when resting your rifle on the magazine.
Once you have them, you'll wonder how you did without.