Blue Spice, Unitab Plus Urinal Tab, Round Design Easily Fits Around Strainer, Screens & Pucks Patented Formula Does Not Contain Para-Dichlorobenzene, A Known Carcinogen Which Is Banned In 10 States, Acid Stable Enzymes Neutralize The Formation Of Ammonia Which Causes Urine Odors, Removes Corrosion & Uremic Salts, Cleans, De-Scales, De-Limes, Deodorizes, & Maintains The Fixture & Drain Lines, Last An Average Of 30 Days. 12 Screens and Pucks Per Box.