DRETCHEL guns use the American style “square notch” trigger mechanisms which accept all American style shafts such as Riffe, Mori, Addiction, etc… The square notch can be seen in the link image below. Euro style will have a half round notch at the back of the shaft and only work with Euro triggers.

I use Neptonics trigger mechs. They offer 3 styles, 1) Reverse Mech 2) Reef Mech 3) Tuna mech. The Reef and Tuna are identical designs except for the housing of the mech. It is square for the reef mech and rounded for the tuna mech. The Tuna mech is the most expensive but I think looks the best and cleanest in the gun. This is my go-to for almost all builds now.