The Works® Bleach Automatic Toilet Bowl Cleaner sanitizes your toilet bowl using the power of chlorine bleach. The Works Automatic Toilet Bowl Cleaner's patented technology slowly releases a concentrated cleaning agent that reduces the need for difficult brushing and maintains a clean toilet bowl for up to 11 weeks - nearly two weeks longer than leading national brands. Better still, it won't harm plumbing or septic systems and can be used in colored toilets. Just drop it in your tank and let The Works Bleach Automatic Toilet Bowl Cleaner go to work for you! Cleans up to 20% longer* Available in 3.5 oz single packs and 7 oz twin packs Cleans & deodorizes with the power of chlorine Kills and prevents the growth of germs; killing 99.9% of germs for 11 weeks Easy to use, just drop in your tank Safe for use in colored toilets Won't harm plumbing or septic systems *As compared with leading national brands in an independent study