Teaching with rescue masks can get costly when you have to replace expensive valves. Now you can get the most from your training dollars with these affordable, individually wrapped, single-use Practi-VALVE® . These convenient, one-time-use valves feature a unique air filter that obstructs the flow of contaminants. The Practi-VALVE® fits on the inside opening of all WNL adult masks, as well as our infant mask opening. Single use only. Discard after use. *Always replace the mask’s original valve and filter assembly after training. LATEX FREE