Mastercool 90066-2V-110B Two Stage Vacuum Pump 6 CFM is designed with a high volume fan to directly cool the pump in addition to a built-in check valve to prevent oil from flowing back into the system in the event of a power loss. The Mastercool 90066-2V-110 features a dual voltage design, ergonomic non-slip cushion handle, cooling fins to reduce pump temperature in extended operation, a gas ballast that pumps water vapor into the atmosphere instead of letting it accumulate in the oil reservoir, and more.