This 16 Windmill aerator looks more like traditional farmWindmills and is more stable than the three legged units. This unit also pumps a large volume of air and has high pressure capability due to large head size for deeper ponds. One piece welded steel hub secures easily toWindmill. Includes 100 poly tubing and EPMD2 differ. 6 diameter head with 12 blades and a tapered blade design allows theWindmill to turn in lowWind and yet produce large air volume in highWinds. Windmill pumps 2.9 CFMat 9 MPH Wind and up to 5 CFM in higherWinds. The tail section turns head 12 15 degrees away fromWind to protect from over speed conditions. Intake air is filtered. Filter is reusable and easy to clean. Keeps dirt, pollen and debris from plugging up pump. Three year limited manufacturers warranty.