we smg8 hpa adapter, it’s a m4 mag adapter. it has the hose already on, the “mag” is 3d printed, i got it from tapp airsoft. i have m4 mags that i could throw in for $7 a piece, there all mid cap. $105 plus shipping, brand new this was around $200, it’s never been fielded i used it once to test it other than that it was hardly used.