Designed to be used in conjunction with the Blue 60 PU foam, these intumescent strips are inserted around the frame fixings to provide the foam with a uniform surface during expansion and help prevent the foam flowing out onto the floor under its own weight. With a length of 100mm these packer strips are also available in 1mm (green) and 5mm (blue) thicknesses, all to suit gaps of 7mm to 30mm between the frame and wall. A typical single door set will require around 33 packer strips, depending on the gap width and which thickness of the packer strips was chosen.