The extra filter in the package is an asthma filter, suitable for people with asthma or angina who suffer from the cold. Because it conserves heat more effectively, it can be used to ward off hypothermia in the event of an accident.
During use the filter gets very damp, and you should clear it regularly by blowing vigorously through the mask. Avoid touching the wet filter as it tears easily. Allow the mask and filter to air dry. Always bring along spare filters on long training sessions and mountain trips. Spare filters must be kept dry.
Race Filter (high volume airflow) sold separately. Filters that are adequately dried between uses should last 20-30+ sessions. 70104