The TAC21 Tactical is a Gas Sniper Rifle and an official licensed product with full trademarks and logo from Modular Driven Technologies (MDT).

The TAC21 Chassis System is CNC Machined from aviation grade Aluminum with Anodized finishing.
CNC engraved MDT TAC21 marking and unique serial number.
One Piece Fluted Outer Barrel is CNC machined from aviation grade Aluminum.
With a top full-length MIL-STN-1913 accessories mounting rail. The built-in mounting rail has 20 MOA (Minutes of Angle) on the action housing and is parallel to the barrel  axis on the fore-end.
2 pcs of side rail and 1 pc of bottom rail are included.
Steel Flash Hider with military grade surface finishing.
Equipped with Magpul PTS MOE Grip & Magpul PTS PRS Stock. (KA-AG-175-BK/DE) 
Equipped with CAA official licensed CBS+ACP Stock (Collapsible Butt-Stock & Adjustable Cheek Rest) and Enhanced Pistol Grip for King Arms M4 / 9mm GBB series with non-slip ergonomic  designed. (KA-AG-175-BK/DE-V2) 
Compatible with M4 AEG stock & tube.
Compatible with M4 GBB grip.
MDT TAC21 Tactical Rifle – Dark Earth - Version II