UniRac 307115M Adjustable Tilt Leg Kit can be used on both flat and pitched surfaces with the standard SolarMount rail. They are designed to minimize the vertical height of your array to hide an array behind a parapet, for example. You can also optimize tilt angle on a pitched roof to maximize system performance. The necessary tilt angle depends on leg length and the make and model of your PV modules. See the Tilt Leg Installation Manual under the Documents tab for more information.