easily operated battery-powered fan with particle or combination filters; the SR 500 is a battery-powered fan that, together with a filter and an approved hood, is part of the Sundström powered air-purifying respirator system; the SR 500 can be used as an alternative to filtering respirators in all situations for which they are recommended; this is especially true for work in harsh conditions, in heat, or for prolonged work; the human interface can consist of a hood, face shield, half mask, or full-face mask; the fan is equipped with a filter and the filtered air is supplied via a hose to the human interface R 500 EX — certified for explosive environments - EX