The structure comprised three fabric layers and incorporated a window and a zipper to allow the astronaut to enter and exit the ball.
The ball would have been connected by an umbilical to the shuttle to supply air until the airlock depressurized.
[1] The PRE was designed to be used in conjunction with a fully suited astronaut that would provide mobility to the person in the ball.
[1][2] The ball's life-support systems consisting of oxygen and a carbon dioxide scrubber could support a person for about an hour.
[3] The ball was made of fabric, and was sealed by way of zippers, with a small circular window to allow the occupant to see out.