Resmed Headgear For F20 Masks Size LargeResmed Headgear For F20 Masks Size Large The entire mask comes with a standard headgear size. However, many people need a bigger size than standard because they have bigger heads. Therefore, ResMed created the large headgear size. Note: The headgear is the part that wears out the fastest because the Velcro straps stop working in a short amount of time. If your Velcro strap stops working then it is important that you change it immediately. We recommend