Replacement inhalation & exhalation valves for 3M™ Secure Click™ Half Facepiece Respirators HF-800SD Series Replacement part for 3M™ Secure Click™ Half Facepiece Respirators HF-800-02 Valve is used as both the inhalation and exhalation valve in the HF-800 Series facepieces Exhalation valve directs exhaled breath and moisture downward Inhalation valve allows filtered air to pass into the respirator Helps maintain regulatory performance requirements of respirator The 3M™ Secure Click™ Inhale & Exhale Valve HF-800-02 is a replacement part for 3M™ Secure Click Half Facepiece Respirators HF-801SD, HF-802SD, HF-803SD (sold separately). Replacement valve is easy to install and can extend the service life of respiratory protection equipment and potentially result in cost savings.