Maxx Model CNC ALUMINUM Hop up Chamber M4A PRO Echo 1 Airsoft Guns The included magazine is G&G's The included magazine is G&G's standard 450 round real size high capacity magazine BLT M 005 VSR 5mm and OD12mm are sold separately) Mounted the removable CNC Brass Side Wings to slide smoothly into the outer barrel slots Included an advanced CNC Delrin Locking C Clip to hold the inner barrel tight in place without wobbling and twisting Equipped with 2 compression springs on top and center to ensure the hopup unit is seated straight and air tight during use Specially designed with a new BB Latching System to prevent BB dropping after removing the magazine The Latching Arm can also be manually pressed to release the remaining BB from inside the hopup chamber Compatible with any 11mm inner bore AEG Gearbox HPA Engine nozzle outlets The Dual UV LED Tracer Module to glow BB in the dark ready (Inlet Adaptor OD11