Size: 37mm "As recommended in MDHS 14/3. Uses 37mm filters or foams at a flow rate of 3.5 l/min. Gives results that closely follow the CEN inhalable convention and can be used for PM 2.5, PM 10, Respirable and Bioaerosol sampling using foams (see Health and Safety Laboratory report IR/L/A/97/19 by L Kenny and J Stancliffe - copy available on request). Manufactured from conductive plastic. Supplied with Inhalable Cassette "