Harpic Flushmatic Toilet Cleaning In-Cistern Block is a drop-in tank tablet which can be used for any accessible cistern. It works by creating strong foam every time you flush the toilet, which helps to maintain the cleanliness and disinfection in the toilet bowl. Harpic Flushmatic toilet cleaner works from inside the cistern to release a dose of powerful detergent with every flush. Distributing the liquid across the bowl, it helps you maintain a hygienic and deodorized toilet and prevents the build-up of stains giving you a continuously clean toilet. You need not remove the pleated cloth wrapper on the block as this will dissolve in the water till it finishes, just drop the block directly into the cistern. For best results drop it at the opposite end to the water inlet, by the float. Wait for 10 minutes to let the block mix, before the first flush.