Blasts crud from tank walls and cleans sensors. Super-concentrated enzymatic blend with Micro-Foam action works overnight, even in hard water. Used regularly, it helps prevent odors and build-up in RV/marine holding and portable tanks. Works on waste, tissue, soap scum and grease build-up that cause sensors to malfunction. Made in USA. | Thetford Tank Blaster Holding Tank Cleaner, 4-pack