The California Air Tools 20040DSPCAD Ultra Quiet and Oil-Free Air Compressor with Air Drying System and Auto Drain in a Soundproof Cabinet is designed to be one of the quietest 4 HP air compressors in the industry having only 65 decibels of sound. The (2) powerful 2 HP motors operates at only 1680 RPM creating less noise, vibration and creating less wear. The Oil-Free Dual Piston Pump System is engineered for longevity, high performance and durability. The SP-Motor/Pumps are tested for a minimum pump life of 3000 hours before service. 30% more life before service. The sturdy steel soundproof cabinet has a large 20 gallon steel air tank and caster wheels that makes it easy to move. The interior of the cabinet is lined with acoustic sound proofing foam insulation to reduce the air compressor's noise and vibration. The 2 latching door handles allows for easy access to the air compressor. The four exhaust fans are designed to remove the air from the cabinet for a cooler running air compressor. The Air Dryer is specially designed to remove the water vapor from the air to protect sensitive tools and machinery. To dry the air from the air compressor an Aftercooler and Dryer are utilized. The aftercooler is a heat exchanger for cooling the discharge air from the air compressor. The water vapor from the compressed air is condensed into liquid form and pushed into the Air Dryer. The factory installed California Air Tools EZ-1 Automatic Drain Valve has been designed to eliminate manually draining your air compressor air tank. The manually set timer allows you to set the time for both the frequency and duration of the draining process. This air compressor is ideal for anyone working inside (office, shop, store, warehouse or home) where noise is a major issue.