Replacement G4 grade filter for Nuaire MVHR units as below: MRXBOX95-WM1 MRXBOX95AB-WM1 MRXBOX95AB-ECO1 Dimensions are 175mm x 270mm The manufacturer of the unit suggests the filter be changed every 6 - 12 months or sooner if required. Manufactured in the UK for Mouldstop. These filters are in no way associated with the unit manufacturer. The use of the manufacturer name and any unit images are solely to aid in the identification of the correct filters.