A seal for a respiratory mask comprising: an oral sealing portion configured to seal around a user's mouth, and a nasal sealing portion configured to seal on the lower surface of a user's nose and be fully positioned below a bridge of the user's nose, wherein the nasal sealing portion comprises: a first upward extension and a second upward extension, wherein each of the first and the second upward extensions has an internal wall configured to engage with a lateral side of the user's nose, and an external wall configured to provide structure to the nasal sealing portion, the internal and external walls being joined along an upper edge of the seal, and wherein the external walls comprise a pocket having a wall thickness that is less than the surrounding wall thickness, characterised in that the external walls further comprise a thickened rib extending along an upper portion of the external wall, wherein the thickened rib is proximate to but spaced from the upper edge of the seal, wherein the thickened rib has a wall thickness that is greater than the surrounding wall thickness, and wherein the thickened rib extends from a rear end of the external wall towards the front of the seal. an oral sealing portion configured to seal around a user's mouth, and a nasal sealing portion configured to seal on the lower surface of a user's nose and be fully positioned below a bridge of the user's nose, wherein the nasal sealing portion comprises: a first upward extension and a second upward extension, wherein each of the first and the second upward extensions has an internal wall configured to engage with a lateral side of the user's nose, and an external wall configured to provide structure to the nasal sealing portion, the internal and external walls being joined along an upper edge of the seal, and wherein the external walls comprise a pocket having a wall thickness that is less than the surrounding wall thickness, characterised in that the external walls further comprise a thickened rib extending along an upper portion of the external wall, wherein the thickened rib is proximate to but spaced from the upper edge of the seal, wherein the thickened rib has a wall thickness that is greater than the surrounding wall thickness, and wherein the thickened rib extends from a rear end of the external wall towards the front of the seal. a first upward extension and a second upward extension, wherein each of the first and the second upward extensions has an internal wall configured to engage with a lateral side of the user's nose, and an external wall configured to provide structure to the nasal sealing portion, the internal and external walls being joined along an upper edge of the seal, and wherein the external walls comprise a pocket having a wall thickness that is less than the surrounding wall thickness, characterised in that the external walls further comprise a thickened rib extending along an upper portion of the external wall, wherein the thickened rib is proximate to but spaced from the upper edge of the seal, wherein the thickened rib has a wall thickness that is greater than the surrounding wall thickness, and wherein the thickened rib extends from a rear end of the external wall towards the front of the seal.