This is a very unique 1960's / 70's era Specialied flight engineer helmet w/ oxygen mask for his altitude, earphones and microphone. It came from an elderly man who worked for IR Properties - a company that flew aircraft that sought out "Flying Infrared Signatures from Technology Aircraft". The man was a flight engineer for many years and in the Air Force beforehand. The helmet / hat has it's original oxygen mask, headphones, and microphone. I know NOTHING more about this item or ho...w it works. It makes a great display piece or memorabilia for someone interested in flight engineering.