This is a custom designed laser sintered nylon adapter that allows you to use HPA (high pressure air) and Echo1/Cyma MP5 AEG magazines on your Hi-Capa airsoft pistol. To use it you will also need an MP5 AEG magazine, “paintball” tank with low pressure regulator (0-140) psi, a hose with a Foster (polarstar) quick disconnect and of course bbs. The normal operating pressure for green gas is roughly 120 psi depending on the temperature. We recommend that you run you pistol near this pressure and do not exceed 140 psi. Keep in mind that higher pressures can cause excessive wear and damage to the internal components of your airsoft pistol.