Replacement filter cartridge for Radex breathing air filter. Replace every 3 months. Sooner if using oily or moist air. Will not remove Carbon Monoxide. Suits for RPB Radex and Bullard Breathing Air Filters, Replacement Carbon filled Breathing Air Filter, Removes unwanted smells and air impurities, Does not remove CO Carbon Monoxide, Filter cartridges must be changed every 3 months or 400 hours usage – whichever occurs first, because the charcoal is activated when opened, Sold Individually and Genuine Parts – Manufactured by RPB Safety