walther quickfill slangeWalther has made a hose that fits directly on their 6 liter air tank. It screws directly into the pressure tank and has a thread on the other side if, for example, you have a threaded filler neck. If you have a filler neck with QD, you must purchase a fetal coupling, which can be found under "Additional Purchases" When this is installed, you can also fill air directly into the smaller HPA tanks.