I work for a medical supplies store, and one of our major equipment deliveries is a cpap machine. It is used by patients with sleep apnea. The cpap machine its self is very small, but it also can come with and oxygen machine that can be much larger. When you get a cpap machine, it comes with the mask that is worn either over both the nose and mouth or just over the nose, and the clear tubing that connects the mask to the machine. The cpap machine is prescribed therapy from your physician, and most insurance companies do cover it.