PARKEL RV and Marine Sensor Cleaner is an essential rv accessories when purchasing an rv camper. Our extra strength bio-enzyme solution is safe to use and will properly treat and clean your black holding tank. With easy DIY methods by pouring through the toilet, it will naturally break down all brands of toilet paper and eliminate awful camper sewer smells. Your RV and Marine black tank no longer needs to smell bad and it will restore level gauges. In addition to preventing pyramid plugs and tank clogs, it will also clean your sensors. PARKEL RV and Marine Sensor Cleaner is an essential accessories when dealing with camper toilet treatment and rv stuff. Please note, this item also works in grey tanks too , with water as well.