Camco's TST Hibiscus Breeze Drop-Ins help control unwanted odors and break down waste and tissue in your black water holding tank. These easy-to-use drop-Ins contain a blend of hibiscus breeze-scented surfactant oils that trap unwanted odors in your tank, making your camping experience more enjoyable. TST Hibiscus Breeze is RV and marine approved, does not contain formaldehyde and is safe for all septic tanks—it's even great for portable camping toilets!