Whether you’re a Diamond Medallion member, American Executive Platinum, or if you only travel once a year, try your luck to see how many of these 15 Hidden Airplane features you know, as The Cheat Sheet describes. Some include hidden handcuffs, secret sleeping compartments, surveillance cameras, and more.

Per The Cheat Sheet:

• Secret handcuffs: You never know what type of passengers you might be dealing with up at 35,000 feet, which is why every airplane is equipped with hidden handcuffs in case the flight crew needs to restrain disruptive passengers.
• Surveillance Cameras: After 9/11, airlines starting adding surveillance cameras onboard their planes. JetBlue Airways has cameras on all their flights recording a 24 hour feed, so they can see what’s going on at all times. Have you spotted security cameras on other US airlines before?
• Tiny Hole in Each Window: Whether you prefer the window or the aisle, chances are you’ve noticed that small hole in every window at the bottom. It’s a feature that protects against the pressure drop, as the aircraft climbs or descends several thousand feet, protecting it from shattering.

See if you know of any of these hidden features that the article mentions.