Lwrc six8-spr 6.8 spc 16" 30rd black FEATURES-Proprietary upper & lower receiver optimized for the 6.8 SPC IIcartridge-MagpulA(R) high reliability 30-rd magazine with high-visibility follower-Enlarged ejection port -Skirmish(TM) back-up iron sights-16.1" cold hammer forged NiCorr-treatedbarrel-1:10 twist rate-5/8 x 24 muzzle threads-12" user-configurable rail system-Compact stock w/ integral sling attachment point-Short-stroke piston operation-Enhanced fire control group: Our investment castings are x-rayed for inclusions prior to machining & nickel-boron coated for a smooth crisp trigger pull with positive reset-High efficiency flash hider-Ambidextrous charging handle Other Features: Piston operated, aluminum upper/lower receiver, 12" modular rail system, skirmish sights, ambi controls/charging handle uses unique magpul 30rd magazines-standard 6.8 ar-15 magazines will not work.Specialized upper and lower not interchangable with ar15