This unit is stationary in design to provide a continuous supply of breathable air. Five stages of treatment provide compressed air one million times cleaner than we normally breathe. Stage 1 is Grade AA, followed by stage 2, an absorption bed of activated carbon (AC), stage 3 is a twin tower heatless regenerative air dryer, stage 4 is a catalyst and stage 5 is a final filter (AR) for "polishing" the air.