Possible Clues:

• High-altitude pilot's equipment
• Presumably, you could buy this from 20 across and from relative from Saskatchewan for one taking a breather
• Inspiring invention for when the pressure's off?
• Breather?
• Drop-down item that hopefully doesn't have to
• Bovine breathing aid?
• Breathing aid
• Breathing device placed over mouth and nose
• Vital accessory for high-fliers
• Device worn over nose and mouth to aid breathing