Only use genuine PowerCap® Infinity® filters supplied in pairs from JSP Ltd or its distributors. Always replace both filters simultaneously. NEVER use compressed air on the filters. This will seriously limit protection. PowerCap® Infinity® delivers TH3 protection with a Nominal Protection Factor of 500 (UK APF 40). TH3 is the highest possible rating in the EN 12941:1998 + A2:2008 standard.