The EVA fits over the helmet. The bar is designed so that the astronaut can take a bite and pull the remainder up. The entire bar must be eaten at once to prevent crumbs from floating within the helmet. However, most astronauts prefer to eat prior to the spacewalk and not use this bar. The PLSS is the backpack worn by the astronaut.
Oxygen flows into the suit behind the astronauts's head and out of the suit at the feet and elbows.
Once inside the PLSS, the air flow enters a charcoal cartridge, to remove odors, and then the carbon dioxide scrubber cartridge. The gas flow then goes through a fan, and then to a sublimator that removes water vapor and returns it to the cooling-water supply. The PLSS provides up to seven hours of oxygen supply and carbon dioxide removal. The EMU battery is made of 11 zinc cells connected in series. The battery provides about 27 amp-hours of electrical current, and can be recharged inside the shuttle.