Bostik Seal 'N' Flex® 1 is a low modulus, one component, Class-A polyurethane sealant. When cured it will form a tough and flexible seal capable of cyclic expansion and compression movement of 100% (+ 50%) of the original installed joint width. Where to Use 600ML Interior surfaces Exterior surfaces Commercial applications Heavy commercial applications Substrates Precast panels Tilt up panels Brickwork Blockwork Aluminium windows Materials Granite Sandstone Marble GRC and CFC Fibreglass Plasterboard Concrete Plasterboard Fibre cement sheet Aluminium