RhinoFLEX™Singles™ 4 oz. 8 Pieces Holding Tank Treatment by Camco®. Holding Tank Treatment features a bacteria/enzyme to digest waste and break down tissue for easy biodegradation. This product harnesses the natural process for which nature digests waste. Just 2 ounces treats a 40-gallon tank. Features a fresh pine scent. Unlike most enzyme treatments, this new chemistry provides a stable product with a long shelf life that is not temperature sensitive. It also contains a buffering agent to prevent acid formation and septic odors.