This headgear is a replacement specifically for the AirFit N20 Masks and is not compatible with any other mask models. Our N20 headgear is a suitable replacement when you find that your mask is starting to sit more loose over time, the mask shifts awkwardly and develops leaks or basically, your current N20 headgear is suffering from general wear and tear due to regular use. Our Headgear deterioration can also occur due to incorrect cleaning methods (by using a powerful detergent etc). As a rule of thumb and best practice, we suggest that you look to replace your AirFit N20 headgear every three months or so.