The Auto-Air™ Cart contains an Auto-Air™ Breather Box® to provide Grade-D breathing air while continuously monitoring for Carbon Monoxide (CO). In the event of electrical failure or air pressure failure, the reserve air activation automatically switches to the reserve air cylinder(s). A pneumatic or electronic reserve air system consisting of twin air cylinders provides back-up air. Select the cart size based on the desired amount of users and reserve air needed to allow workers to safely egress the work area in an emergency. Carts operate with 2216 to 5000 psi cylinders (sold separately).