That is basicly the same thing as the fuel dots that I use only in black plastic. I think the machined aluminum ones look much better though. I put a small pick-up bottle under the 2 pipes from the pitts muffler coming out of the bottom of the cowl & listen closely. With a hand crank pump I can hear a little gurgle just before it is full. With my electric pump I can hear a difference in the sound of the electric motor just before it is full. As soon as I hear the difference I shut it off & just a few drops runs into the pick-up bottle which I then return to my fuel jug. It seems to work well enough for me. Hope that helps.