The SR 710 particle filter is provided with a special thread and is designed for use in the Sundström SR 500/ SR 500 EX/SR 700 battery-powered fan as a separate particle filter, i.e. it cannot be combined with a gas filter. The filter is of P3 R* type and provides protection against all types of particulate pollutants. If a combined filter for fan SR 500/SR 500 EX is needed, the gas filter should be combined with the SR 510 particle filter. The filter should be combined with prefilter SR 221 in order to increase its useful life. * R (Re-useable): The filter is intended to be used for more than a single shift.