TST MAX Orange RV Toilet Treatment Drop-Ins *10-Pack 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, and a blend of orange-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!