Air Systems® BB100 Breather Box® with Blast-Air™ Cart meets OSHA requirements for Grade D breathable air. This system includes the carbon monoxide (CO) monitor, Filter Change Indicators on all filters, incoming 1/2" Industrial Interchange Air Plug, three stage filtration, two 300 cfm rear pre-filters with auto-drains, remote alarm jack, external warning lights and alarm, and is mounted on a steel cart with pneumatic tires.