Maxx Model CNC Hop Chamber M4E (Standard M4)This is Maxx Model's latest & newest hop chamber. This chamber accepts normal AEG buckings and has been slightly re designed from older models. All new hopups no longer use screws on hopup arm, replaced by oring to keep the pivot pin, updated internal design tighter tolerances to improve consistency and accuracy. BB are lined up straight and consistent 95%, BB position is seated consistently and repeatedly after each shot and stacks up perfectly.