The Details:

• ETU for 3 round burst
• Pre-installed MOSFET
• Li-Po Ready
• Rotary Hop-Up
• 450 Round Magazine
• Full Metal M-LOK Rail

 The G&G GC16 ARP-556 M4. This G&G airsoft gun includes a lipo battery, charger, MOSFET and uses M4 Mags. 

Length: 500mm - 590mm (adjustable)
Weight: 2350g
Inner Barrel: ~150mm
Magazine Capacity: 350 rounds. G&G and other compatible M4 Series AEG magazines
Thread Direction: 14mm Negative
Gearbox: Ver 2 Full Metal, Fully Upgradeable
Motor: Long Type
Fire Modes: Semi/Full-Auto, Safety
Battery: 7.4V Small Type recommended (Battery not included. Wired to buffer tube with small Tamiya connector)
Hopup: Yes, Adjustable
Package Includes: Gun, Magazine, Lipo Battery, Charger