Twist & Seal Plug is where things get trickier. This is simply an adapter to get the hose connected to a quick disconnect(QD). I wanted stainless steel for all of our QD to ensure they last longer. This part is brass and will be threaded permanently, so I think it's sufficient. The outlet hose from the pressure washer is brass anyway.
Inlet = M22 (National Pipe Thread) NPT Male: This M22 male threaded end screws into a female M22 connection.
Outlet = 3/8" (National Pipe Thread) NPT Male: This 3/8" female male threaded end screws into a female 3/8" connection.
Kranzle K1122TST Hose Outlet -> MTM Twist & Seal M22 X 3/8" Male Plug -> MTM 3/8" Female QD Coupler -> MTM 3/8" Stainless Plug -> Mosmatic Spray Gun Inlet
*If you want stainless for this part, I can get you one, but I don't use one.