That brass adapter with the tape on it is something we send with our Original Mosmatic/MTM sprayers along with the stainless 3/8” coupler in order to connect to a pressure washer hose. We also sent a 1/4” BSPM to 3/8” NPT adapter that actually replaces that brass piece for the Comet systems. We send the brass piece anyway since it comes with the kit, but you don’t need it. Just connect the 1/4” to 3/8” adapter to your hose, the stainless coupler to that, then plug your gun in and you’re good to go.