The legendary Hadron Airsoft Designs G17/G18 TDC has been re-designed and improved for 2023. This part allows external adjustment of the G17/G18 Hop up. Best to use good quality rubber, (ideally the Snipermechanics Flamingo 50 or 60), and use good quality 0.3 to 0.5g bb. Relocated TDC hop pressure point, and twin barrel securing system. M3 finer thread for accurate adjustment. Internally threaded outer barrel, just add the usual m11 to m14ccw adaptor. Spiral outer barrel design. Fitting:- Remove slide, and remove the existing outer barrel assembly. Open hop unit barrel assembly, and remove the hop wheel. Re-assemble with a quality bucking, Flamingo or ML Autobot 50 series. ML Crazy jet barrels work exceptionally well in the setup. Insert an H-plate or Fang if required (ideally use for 0.4 and above). The H-ARM v2 also fits certain hop units. Rebuild, and  when fitting the HAD outer assembly, ensure to nip up the side securing grub screws. DO NOT OVER TIGHTEN. Once the inner/outer are replaced in the upper slide, add the grub screw to the TDC. Refit the upper to the lower, and check slide to TDC grub clearance.