12 packets TST Drop-Ins Chemical - Camco RVs TST Drop-Ins are designed with great odor stopping power and contain No formaldehyde. They have a non-staining formula that helps breakdown waste and are also safe for septic tanks. These handy and convenient individual dose pouches come in an easy-to-use resealable bag, simply drop in one pouch and you can treat an entire 40 Gallon tank. When you add water, the plastic pouch dissolves and instantly eliminates odors on contact. Marine and RV approved. *WARNING: Keep Out of Reach Of Children and Pets. Harmful if swallowed. Avoid contact with food. 12 drop-in packets per box.