The Magpul Tactile Lock-Plate is a magazine enhancement that provides the user with the ability to rapidly and easily identify/differentiate magazines with mixed loadouts such as ball tracer supersonic and subsonic types via raised tactile features. These features are 1/8″ raised ridges that protrude through the magazine floor-plate opening and are purposely pronounced at an optimum height to ensure functionality with gloved hands. The Magpul Tactile Lock-Plate comes in two fully distinct configurations of 1/8 raised ridges: Type 1 – single ridge and Type 2 – double ridge. These designs provide the user with the ability to quickly and confidently identify three separate loadouts by tactile feel when utilized in conjunction with standard floor plate/lock plate combinations. Full functionality remains with the magazine inserted in a weapon or in a magazine pouch.Fits standard PMAG 10/20/30 AR/M4 GEN M3 and PMAG AR 300 B GEN M3 floor-plates. *Note- NOT COMPATIBLE with PMAG 40 AR/M4 GEN M3.