This is a Odin Works Mag Release known as the XMR, model ACC-XMR3-BLK.
Inspired by the ODIN Works O2 Lite" the XMR3 is the latest mag release available from ODIN Works. Machined from billet 6061 aluminum and designed to work with KNS pins and the BAD lever. The XMR3 has the largest profile yet" making it easily accessible by all shapes and sizes of hands and fingers. Works with both AR15 and AR10 lower receivers. Easy install that takes minutes.
Features:
Compatible with BAD Lever
Compatible with KNS Pins
.1 oz (including paddle, button, and screws)
Large surface area for quick magazine reloads
Easy to reach
Ergonomic design
Release magazine without changing grip or position
Contoured for positive depression and reduced slip