G&G Armament has their 18K engine here which fits in most weapons

and regular pockets as well

This model is non-blowback

Mask Protection v11

Axil Trackr Tactical Aktiv Høreværn 036-kugler G&G Armament has their 18KAxil Trackr Tactical, also called SportsEar Trackr, is an active hearing protector that has a fairly compact design that makes it really suitable for when you go hunting or on the shooting range. The hearing protectors here amplify the sound up to 40 dB and automatically block sounds above 85 dB, so they are "turned down" to a comfortable sound. They are both water repellent and keep sweat out and they are built in such a way that they can reduce wind