A 1200 x 600 x 50mm intumescent fire batt (coated mineral wool board) is a high-density structural fire-stopping panel designed to seal mechanical and electrical service penetrations in fire-rated walls and floors. Constructed from a rigid stone wool core pre-coated on one or both faces with a protective fire-retardant ablative coating, it provides up to 2 or 4 hours of fire integrity and thermal insulation (EI rating). Under extreme heat, the coating expands (intumesces) and forms a solid seal that prevents the passage of fire, smoke, and toxic gases around pipework, ducting, and cable trays passing through compartment walls.