The TST MAX Drop-Ins help control unwanted odors and break down waste and tissue in your black water holding tank. The easy to use drop-ins contain a special chemical that helps break down waste. They also have a blend of ocean-scented surfactant oils that trap unwanted odors in your tank, making your camping experience more enjoyable. The drop-ins are RV and marine approved, non-formaldehyde and safe for all septic tanks—they’re even great for portable camping toilets! Comes with (30) drop-ins.