Included O-ring prevents air volume loss even at higher velocities and powerful builds

and it falls into the first category

2300R Drum Magazine for M4/M16 (Manual)

Using high quality batteries such as this 7

SS Airsoft IGL Standard Weave Kythera (Green) Warhead Industries Included O-ring prevents air volumeThe Integrated Grip Line or IGL is Airsofts original solution for replacing the weak and flimsy macro line that typically powers HPA conversion for airsoft replicas. The IGL is available with fittings compatible with most HPA units on the market from manufactures like Polarstar, Redline, Wolverine and Protech. The IGL is constructed from a durable, widebore line and is available in many different colors. Every piece is hand made and tested right here