Light weight nylon polymer free float modular rail interface system for attachments.Light weight nylon polymer upper and lower receivers.Upper Picatinny/Weaver style rail for optic accessories.Internal full metal Version 2 Gearbox with 8mm gear bearingsInner barrel measures out to 343mm in length.6.03mm inner barrel diameter size.Fully adjustable retractable stock for stability.Easy access for quick spring change system.Single sling placement w/ 3-hole buffer ring.Included 300 round AEG metal magazine w/ nylon polymer winding wheel.Flip-up front and rear sights w/ locking clamps.