These are 3d printed Mag Holder for the AR15. It attaches around the magwell and allows you to carry a 2nd mag. When you depress the mag release on your AR15 it also releases your 2nd mag allowing for a fast swap. Has mag catch just like your AR15 allowing the 2nd mag to be saftely secured during opperation...
Tried to capture the design while on an AR15 but also included a picture of the part by itself...
Can ship at buyers expense...probably looking at $5-$7 shipped...
Please dont hesitate to ask questions...