Commonly fitted above the ceiling plasterboard and separate from Diamond Dome Ceiling Diffuser the intumescent fire choke collar consists of two steel parts which clamp around the aluminium sunpipe tube, designed to crush the aluminium tube. Creating a solid barrier, when exposed to fire which is rated to prevent the spread of fire into the roof space by up to 2 hours. Designed to be fitted easily to your Diamond Dome 450mm sunpipe system, the Diamond Dome Sunpipe Intumescent Fire Collar is designed to delay fire spreading into the loft space.