A respiratory mask assembly for delivery of non-invasive positive airway pressure to a user having a rigid mask shell including a plurality of slots; a soft cushion including at least one flexible sealing lip constructed and arranged to extend around an inner periphery of the cushion and to deform to provide a continuous airtight seal between the cushion and the rigid mask shell, the at least one flexible sealing lip being constructed and arranged to return to a relaxed state when the cushion is disassembled from the rigid mask shell, the soft cushion including a retaining portion; and a retaining ring configured to engage with the retaining portion of the cushion, and including a plurality of clips each positioned on respective spring arms to engage with each of the respective plurality of slots of the rigid mask shell to retain the cushion in position with the rigid mask shell.