The Works Toilet Bowl Cleaner is inexpensive and easy to use. It WORKS! Kills 99% of household bacteria - Salmonella choleraesuis, Escherichia Coli and Staphylococcus aureus. The Original Formula is tough on stains yet safe for septic systems. Remove rust, lime, scale, and hard water stains on contact. Each bottle is 24 fl. oz. and there are 12 bottles to a case.