The Mission First Tactical AR15/M16 Mag Coupler is now at RedWolf Airsoft where you can get one for US$16.00... "This M4/M16 Mag Coupler is a military grade polymer magazine holder designed to hold two M16 style magazines together, especially when you need extra ammo capacity. This mag holder will also allow you to load your magazine faster. It will fit your PMAGS or other metal magazine perfectly. Available in different colors including Dark Earth, Grey, Foliage Green, and Black."