Nilfisk GM210 GM310 GM320 and GM340 and GM410 GM420 and GM430 and Nilfisk Silver and Gold Nilfisk Spring Xtra and Arnoldi domestic vacuum cleaner HEPA paper cartridge filter. It went behind the dustbag and comprised of 2 elements in the box, the pre-filter, and HEPA cartridge filter.
AS OF MARCH 2017 ALL GENUINE FILTERS FOR THESE MODELS BECAME OBSOLETE AND UNAVAILABLE.
These filters cannot be cleaned, Nilfisk recommend it's replaced each year. Check it's condition by raising the filter to the sky, dirty side towards you. Looking up, you should be able to see light through the pleats. If you can't it needs replacing.
PLEASE NOTE:
According to EN 60335-2-69 The Terms "TYPE H" FILTRATION and HEPA FILTRATION are NOT INTERCHANGEABLE
The HEPA classification only considers the "efficiency of filtration" eg H10, H11, H12, H13, H14, U15, and U17 NOT the SUITABILITY FOR USE with HAZARDOUS or COMBUSTIBLE dusts