Had my boat in a slip for the weekend here a few weeks ago and it rained pretty good, found out my auto float on my bilge pump was not working so I removed the tank and fixed it, while I was at it I scrubbed everything clean and added this fuel cap. I got tired of putting gas in an ounce at a time so I bought this cap, it has a 3" hole when you pull the plug, I used plastic bonder to seal the vents in the cap off so I wouldn't get fumes in the bilge. BTW, that tank is a pain to get out.