My Rubbermaid 5-gallon mash tun developed a substantial leak in the middle of a sparge last week on brew day. I made it worse and cracked the cooler when I over-tightened. I made a trip to the Home Depot for a new cooler and gasket. I found a Danco "Tip toe drain gasket" that had the exact shape of the cooler wall and thought I would give it a try. For $1.67 each I have both the mash tun and hot liquor tank leak free for a while.