Our eco-friendly hypoallergenic masks are made of lint-free polypropylene fabric. The pleated mask forms a protective air pocket around your face, so the inner surface does not touch your lips even when you are breathing deeply. Elastic ear loops stretch up to 35 cm to ensure that one size fits all. When firmly pressed to the bridge of your nose, the adjustable soft clip prevents air gaps that would allow air to bypass the protective layers of the mask before being inhaled. We do not recommend wearing the same mask for longer than two hours.