FS4004 intumescent aperture liner is supplied 44mm wide to suit 30 minute fire rated timber doors and 54mm wide to suit 60 minute fire rated timber doors. It is only fitted to timber fire doors and is not required on steel fire doors. It is 1.6mm thick and fits all round the inside of the aperture into which the Slimport, LoPro vision frame or FBLS louvre is being fitted. However other thicknesses and widths are available to special order. It is graphite based and in the event of fire it begins to expand at 288°C and expands eighty times its own volume forming a very soft and fluffy char.It is supplied with a PSA self-adhesive tape to one side and is coloured red. The standard lengths are 2438mm (8 feet) and 1219mm (4 feet). It has been included in successful fire tests up to one hour on timber doors with LoPro vision frames and Slimport circular portholes. Copies of test reports WF 190621/A Issue 2 dated 09.05.2013 and WF 190869 Issue 4 dated 09.05.2013 available upon request. NO HARDWOOD DOOR LIPPING IS REQUIRED ROUND THE APERTURE. See page 73 for other sizes.