A non-rebreather mask is a medical device that helps deliver oxygen in emergency situations. It consists of a face mask connected to a reservoir bag that’s filled with a high concentration of oxygen.

Non-rebreather masks are used to deliver oxygen therapy to people who require high-concentration oxygen but aren’t in need of breathing assistance. They’re considered low-flow oxygen delivery systems.

If you've ever traveled on an airplane, you know that masks can drop down to supply oxygen in the case of an emergency. Airline oxygen masks have about a 15-minute supply and typically fall when an ...