| abstract |
A filter cartridge ( 5 ), suitable for attachment to a respiratory mask, has a housing that includes an air inlet ( 27 ), an air outlet ( 39 ), and filter material ( 17, 19 ) through which air to be filtered travels through when passing from the inlet to the outlet. At least part of the housing includes a sheet material ( 23 ) that is thermo-formed around the sides of the filter material. |