A Cast Iron Sleeve Coupler is a type of coupler used in construction and scaffolding applications to connect two scaffold tubes end to end. It is made from cast iron, which is a strong and durable material that is able to withstand heavy loads and harsh environments. The sleeve coupler consists of a tube-like sleeve that fits over the ends of two scaffold tubes and a bolt that tightens the sleeve around the tubes. The Cast Iron Sleeve Coupler is typically used in pairs, with one coupler on each side of the tubes.