This is a CMMG , model 55AFF6E.
Forever the AR15 has been a right handed person's tool. With Ambi controls evolving" it's becoming more of a tool that everyone can use" even left handed shooters! This Ambi Mag Catch works in place of a standard mag catch to allow left handed shooters drop their mag without having to switch to your right hand for the mag release. Easy drop in replacement" and blends in to the style of any AR.
Features:
Compatible with all AR15/M16 rifles
Installs the same as factory mag catch
Includes mag release button and spring