We’re happy to announce that our second wave of CRBN uppers is finally here! They’re a sleek way to turn any Polarstar Fusion Engine build into a lightweight beast, made with REAL Carbon Fiber, for strength and durability. They’ll be available in sizes for 128mm, 155mm, 185mm and 205mm inner barrel lengths. We have limited stock, so if you want to go featherweight, make sure to pick one up! For those without Fusion Engines, no worries! We're developing a gearbox to install the CRBN Upper on ANY HPA (F2, Jack) or AEG replica. CRBN Uppers are EXCLUSIVELY compatible with the MAXX ME Hopup Chamber.