Abstract: An improved nasal puff assembly is provided which is of particular benefit in the treatment of obstructive sleep apnea and which is characterized by a gas-delivery puff which fits only in the nose of the patient and is therefore of relatively small size and can be comfortably worn. The nasal puff of the invention advantageously includes a plenum chamber having an inlet and a pair of laterally spaced outlets; a pair of soft synthetic resin nares elements or pillows are operatively coupled with the spaced plenum outlets and are designed for ready adjustability so that the effective positions thereof can be altered individually for permitting custom fitting of the nares elements with respect to the nares of different patients. In this way a relatively small number of different sizes of nasal puff can be modified to meet the needs of virtually all patients.