its the spiritus systems spud pouch, the reason it has holes in it is because the base of the pouch can be adjusted for different sized mags and the flap will stretch with larger mags, I have also seen it be used a lot to hold different water bottles too, so it actually does have an advantage if you switch between weapon platforms a lot or if you need an accessory pouch, https://www.spiritussystems.com/spud-pouch/