Camco TST Fresh Scent RV Toilet Treatment, Formaldehyde Free, Breaks Down Waste And Tissue, Septic Tank Safe, Treats up to 8 - 40 Gallon Holding Tanks (8-pack of 4 ounce singles) Eliminates odors and lubricates sensors in the RV holding tank Safe for all septic tanks RV and marine approved; non-formaldehyde 8 treatments (1) 4 oz bottle treats a 40 gallon tank