Whink 20223 RUSTGuard Time Released Bowl Cleaner, 4 Oz

2 in 1 Hard Water and Rust Toilet Bowl Cleaner. Safe for plumbing and septic systems. Stops rust with every flush. Outperforms all major bowl cleaners. No other toilet bowl cleaner works like RUSTGuard. Its unique formula is specifically designed to prevent rust and hard water stains - with every flush. Won't harm pets. Safe for use in white AND colored toilets.