YKK's watertight and airtight zippers (through which neither water nor air can pass) are used from the chest around to the back of space suits (pressure suits). air pressure rises dramatically in extremely high-altitude environments, and humans cannot survive. The pressure inside of space shuttles is adjusted to address this problem, but astronauts always wear pressure suits (intravehicular activity clothing to sustain near-Earth pressure through pressurization) during launch and re-entry in case of emergencies to protect them from pressure changes.

These suits are often referred to as orange suits.