VFC MP5 Hopup Arm and Nub V2 vipertech -4140 steel which means it

-4140 steel which means it is corrosion resistant

I would highly recommend utilizing HPA with this recoil spring as I have done zero testing with regular propane gas

(helps to close receivers that previously needed to remove the pivot pin)

-Black Nitrided

Cap only comes with combo package

VFC MP5 Hopup Arm and Nub V2 vipertech -4140 steel which means itThis arm provides more consistent hopup tension on the bucking for more consistent BB backspin. 7075 anodized aluminum. Rubber Nub. This new version is CNC machined rather than 3d printed. This hopup arm allows for the use of a rubber nub which will greatly improve your hopup consistency!