This type of mill is very rare and was only built in and around Belgium. These mills were usually built atop a man-made hill to achieve higher wind exploitation and to create storage space underneath where the carts could be loaded directly. They were usually used to make flour but the energy from the wind could also be used to power a saw mill. According to wind speed, the number of revolutions of the windwheel could be regulated by increasing or decreasing the area of the sailcloth.