Brand new upper receiver only used once Defiance TR210 M-LOK rail The Trident MK2 CRB-M is a modernized carbine that excels in close quarters and wide open outdoor engagements. Inner Barrel: 280mm (6.05mm Diameter) Thread Direction: 14mm Negative Krytac Defiance Flip-Up Back Up Sights (Model: Full Set) Magpul AFG (Angled Fore Grip) Rail-Mounted Forward Grip Noveske Licensed KX5 Sound Amplifying Knights Armament Silencer