The Knockout Mould & Mildew Cleaner from Barrettine is a ready-to-use surface biocide for the control of organic growths with a cleaning action to remove light surface dirt. Can be used externally and internally to eliminate mould, mildew, algae and fungi from masonry, timber, plastic and similar substrates. Competitively priced with great RRP’s which comes in a box of four. The Knockout brand is recognised for quality and has a comprehensive range of cleaners and unblockers at competitive prices.