THIS IS A 2 TO 3 MAX USERS PLEASE SPECIFY IF LARGER UNIT IS NEEDED Our EcoVac system provides the advantages of proven technology, durable construction, quiet operation and oil-free performance with the latest in water and energy-saving features. This is not only important to you as an environmentally responsible business owner, it also prepares your practice for the upcoming change to metered water usage in many areas of the country. We utilize a Variable Frequency Drive (VFD) to control the vacuum levels. With no suction being used, the motor is running one third the speed and using very little power. Every time a suction hose is being used the motor automatically speeds up to maintain constant suction. Maintenance free unit with no traps to clean, no oil to check or change. Truly a ZERO maintenance machine