Rhino Holding Tank Cleaner Drop-INs - 6-PackCamco&';s Rhino RV Holding Tank Cleaner Drop-INs contains a powerful enzyme complex that helps clean your RV&';s black water holding tank. Just (1) Drop-IN treats up to a 40-gallon tank. Cleaning your holding tank regularly helps keep tank sensors functioning efficiently and keeps unwanted smells at bay. These easy-to-use Drop-INs are pre-measured and safe for all septic tanks. This product does not contain pesticides, biocides, or the toxic formaldehyde-releasing ingredient bronopol. For best results, use (1) Drop-IN every three months. Camco makes quality products for RVing, boating, camping, towing, tailgating, and grilling that help you take your passion for the outdoors to the next levelFeatures: Black Water Holding Tank Treatment: Contains a powerful enzyme complex that helps clean your holding tank Keeps Tank Sensors Functioning Efficiently: Just (1) Drop-In treats up to a 40-gallon tank Safe for All Septic Tanks: This product does not contain pesticides, biocides, or the toxic formaldehyde-releasing ingredient bronopol; Safe for all septic tanks For best results, use one Drop-In every three months The product is made in the USA *Sold as a pack of 6 .embed-container { position: relative; padding-bottom: 56.25%; height: 0; overflow: hidden; max-width: 100%; } .embed-container iframe, .embed-container object, .embed-container embed { position: absolute; top: 0; left: 0; width: 100%; height: 100%; }