Hi Everyone... PassageMaker has sight glass tubes (made of clear plastic hose) on both tanks. I have used a marker to indicate how much fuel is required to fill the tanks, i.e., a mark at 100 gals, another at 200 gals. The tubes are about 15 - 17 inches long. I generally wait until I need 300 gals before making the trip to Bellingham to the Shell Fuel Dock where I get their 1000 gal price. The owner, Dick Heay, has extended this offer to everyone in our YC and gave me a bunch of business cards to distribute. Dick generally beats the competitors by at least 10 cents a gallon, thus a trip (2 hours up & 2 hours back) for fuel (300 gallons) makes it worth it. It's also a good run for the boat. During a survey last August the Marine Surveyor gigged me for having plastic tubes instead of glass. His rationale was that the plastic could melt during a fire. Of course, I am not sure if he considered the possibility of breaking the glass tubes if they got accidentally bumped. His point is well taken, however. If the glass tubes did get broken, there is a shut off valve at the bottom of the fitting for the tubes. If the tanks were clear full, the fuel will run out the top until the level reached a point where it was below the top fitting. Anyway.... as Paul said, it sure makes it easy to check fuel levels. I also watch the sight "glass" tubes during fueling to know when I'm approaching full. Have never had a spill through the vent line. Very handy feature, although I have to stick my head down thru the hatch in the saloon sole & use a flashlight to see the levels. Better than a spill, in any case. Cheers & hope to see a bunch of you at Poulsbo. j Jerry & Pam Munson m/v PassageMaker (47' C&L Marine Pilothouse) Anacortes, WA 98221-3158