3M Hf-801Sd Secure Click Speaking Diaphragm Half Mask Small Black3M Hf 801Sd Secure Click Speaking Diaphragm Half Mask Small Black 3M HF 801SD Secure Click Speaking Diaphragm Half Mask Small 3M Secure Click Reusable Half Face Mask HF 800 Series is available as two versions, HF 800 and HF 800SD. The HF 800SD versions have a speaking diaphragm. Both versions are available in three sizes. 3M Secure Click HF 800 Series Half Mask Reusable Respirator helps protect against particulates and a wide variety of gases and