How can you be sure that you have donned your mask correctly? With the new patent pending PressToCheck™ filters you can instantly check that you have the correct seal every time. Comfort FIT IT! Don the Mask - Put the straps and harness over your head and pull the straps to a suitably tight and comfortable fit. PRESS IT! PressToCheck™ - Press the front and backs of both filter covers together to stop air from entering through the filters. CHECK IT! Inhale - No air should come through the mask. Adjust the mask and repeat until it doesn't. Release when seal is made.