This pouches are created for Specops operators, who need to recharge as fast, as they can. Each additional second can save their life. Inside of this pouches placed plastic insertions, which working as a rail for Mag. All of this pouches working with ALL mags, including M4/M16 and similar one. Main minus of this pouches - they don't provide full protection against dust and dirt, but if you are planing to play in CQB - it's the best choice.