Dual one-way discharge valves / Set of 4 Valves
Improved one-way airflow valve provides comfortable breathing by optimizing airflow and reducing heat and moisture build-up. The valve opens upon exhaling, lowering breathing resistance. It closes on inhale making the filters work.
An easy twist seal locks the inner filter in place and blocks unfiltered air.
The valves are replaceable, however, you need to replace the valve only if it damaged.