Replacement G4 grade filters for Envirovent energiSava 200 & 250. Replaces Envirovent part numbers: FILTER-ES200 FILTER-ES250 Dimensions are 193mm x 233mm 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.