Taiwan Gun presents a MOSFET-equipped Arcturus AT-PP19-1 Vityaz AEG... "The mechanism is a new, reinforced gearbox compatible with Marui parts and ETU by GATE and PERUN. Quick spring change system (without pulling out and opening the gearbox), bearing spring guide, bearing piston head, full steel teeth polycarbonate piston, steel gears mounted on 8mm steel bushing to be able to withstand the highest loads.