Fresh Products 2-1-20-C-F Para Super Blocks 20#, CherryA powerhouse odor solution for especially large, smelly areas. The block is long lasting (120 days) and wont dissolve in water. Tough enough to handle even the smelliest sewers, elevator shafts, dumpster areas, garbage collection areas, or water treatment facilities. Just take off the old cover refill and replace it with a fresh one. Perfect deodorant powerhouse for sewers, elevator shafts, dumpster areas, garbage collection areas and water treatment