Harpic

Harpic is the brand name of a toilet cleaner launched in the United Kingdom in 1932 by Reckitt and Sons (now Reckitt). It is currently available in Africa, the Middle East, South Asia, the Asia-Pacific, Europe, and the Americas. The toilet cleaning products marketed under the brand name include liquids, tablets, wipes, brush systems, toilet rim blocks, and in-cistern blocks.

It contains hydrochloric acid (10%) as the active ingredient, along with butyl oleylamine and other ingredients, in an aqueous solution.