Flash Harry Bitumen Mastic Sealer 500ml – Roof & Gutter

Flash Harry Bitumen Mastic Sealer is a flexible, waterproof sealant designed for sealing roof joints, gutters, downpipes, and flashing on residential and commercial buildings. This 500ml cartridge delivers excellent adhesion to metal, concrete, and masonry surfaces with long-lasting durability and weather resistance. Ideal for roofers, plumbers, facilities managers, and maintenance contractors requiring a reliable, quick-drying mastic for permanent outdoor seals.