Iron OUT, the #1 brand rust stain remover, offers Iron Out automatic toilet bowl cleaner, specifically designed to repel rust and hard water stains with every flush of your toilet. The concentrated, long-lasting formula cleans rust away and repels new stains from forming for up to 45 days per tablet. This powerful yet safe formula will not harm toilets, internal toilet components, plumbing or septic systems. Use Iron Out powder or liquid spray first to remove rust stains from the toilet bowl before inserting a tablet. Simply drop a tablet in the tank and let Iron Out automatic toilet bowl cleaner do the work for you.