LAYER 5

Closed off from the vacuum of space by their protective suits, the astronauts must breathe.  A network of ducts carries oxygen to the astronaut from his backpack.  These ducts are kept open and clear by spring-like coils made of a "Zytel" nylon resin.  This type of nylon coil is used in gasoline pump hoses at filling stations, to assure unobstructed flow of fuel from pump to gas tank.

Taken from a 1970s DuPont poster.