The right mask is the one that doesn’t leak and doesn’t hurt. This may vary depending on the size and shape of your face. If you open your mouth while sleeping (mouth breather), you may need a full face mask, but may also be fine using a nasal mask or a nasal pillows (intranasal mask) while using a chin strap. If you feel claustrophobic using a full face or nasal mask, you may prefer a nasal pillows mask. You might need to try out a few masks before you find the mask that is right for you.