Quick acting and long-lasting, Harpic Flushmatic Pine In-Cistern Toilet Cleaner cistern block is a drop-in tablet which can be used for any accessible cistern. Working from inside the cistern, it releases a powerful dose of hygienic cleaning with every flush. It also distributes liquid across the bowl to help maintain a hygienic, fresh toilet while also preventing the build-up of stains. Safe for use with septic tanks and all other toilet cleaners. So go ahead and buy this product online today!