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 pre-filter 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.