It was a safety device for commercial Boilers. What's annoying is that the market really didn't exist before we invented the product. When we launched ours www.k3planet.com/Datasheet-9934-2.pdf suddenly everybody wanted one, and in so doing created a whole new market... then about three years in the copies started...

I shouldn't really complain, I earned good Royalty on each one, and over 300,000 were made before we stopped production. It's just when you're on a winner (simple product, easily made, one unskilled person could assemble more than 100 an hour) , you want it to go on forever...