Commercial pilot oxygen mask.
<video controls autoplay loop>
<source src="https://s3-us-west-1.amazonaws.com/hmt-forum/commercial_pilot_oxygen_mask.mp4" type="video/mp4">
Your browser does not support the video tag.
</video>
They're not cheap! Around $5K new: https://www.skygeek.com/zodiac-inter...regulator.html
And here's astronaut Chris Hadfield joking around with one. 1:44 video:
https://www.youtube.com/watch?v=kLETHLv_0vk
