The expansion is sufficient enough to crush the duct and create an effective fire-resistant seal for up to two hours. Preformed and intended for use with uPVC and FB rectangular ducting. This item has been independently tested, and fully complies with BS476 Part 20 & 22: 1987 and NHBC type approval requirements.
Ten cut-to-fit sizes are available. Dimensions range from 110mm x 54mm to 308mm x 29mm. Installation is simple and requires no tools, special training or mastic. Application requires access to only one side of the duct making this an ideal choice for retrofitting scenarios. Suitable for moist, humid and frosty environments.