Includes an ECU (Electronic Control Unit) ECU provides a self-diagnosis function and low voltage indicator High Capacity 300 round magazine Durable rigid magazine design assists in faster reloads Aggressively designed lightweight skeletonized handrail CNC machined anodized freefloat rail design Quick change spring design easily alters FPS Built-in MOSFET protects trigger contacts and increases response Ambidextrous rear sling point adapts to the user Rotary hop-up adjusts BB spin for optimal precision Ergonomically designed polymer textured grip Functioning bolt catch and dust cover Flip-up front and rear sights enhance target acquisition Multi-position MTR stock adjusts for immediate firing preference 20mm top optic rail mounts scopes, sights, and magnifiers Ambidextrous firing selector and magazine release Laser engraved logo and markings Handrail is capable of equipping tactical accessoriesSpecifications: Operation Electric Blowback Build Metal / Polymer Firing Modes Semi, Full-Automatic w / Functional Safety Muzzle Velocity 421 - 441 FPS (w/.20g BBs) Magazine Capacity 300 Rounds Gearbox Version 2 Gearbox Battery 7.4V or 11.1V Li-Po Mini (Not Included) Hop-Up Yes / Adjustable Weight 6.87 lbs Overall Length 35.75 - 32.75 Inches (Extended / Retracted) Barrel Length 375mm Color BLACK 1X AEG Rifle