Thetford Waste Disposal Products work hard so you don"t have to. Nobody wants to spend their vacation worrying about their RV"s waste systems. So Thetford has put together a line of products so good you"ll never give waste a second thought. Just the way it should be. Choose from the products. AVAILABLE SEPARATELY: Thetford Drain Valve Lubricant, Gray Water Control, Tissue Digester or Waste Digester - word search in our Store for "Thetford Waste Disposal Products". Thetford Level Gauge Cleaner... Restores level sensor operation when it"s coated with tissue, waste or soap scum; Provides superior probe and tank cleaning; Solves a problem, or, with regular use, can prevent one; 16-oz. bottle.