"Nasal masks are typically triangular in shape and placed over the nose. The areas covered include from the upper lip up to the bridge of the nose. They are well-accepted among CPAP wearers because of the wide range of sizes and fits, making finding an appropriate mask for any user very probable. They appeal to those who do not like the feeling of the air pressure directly into their nares but do not need a full face mask, or prefer the extra stability of a nasal mask over the nasal pillows style. The extra cavity size of a nasal mask makes breathing that little bit easier, and the innovations from ResMed, Philips Respironics and Fisher & Paykel continue to make these masks smaller, lighter and comfortable." https://innerpeacehealth.in/respiratory-products/face-mask/nasal-mask