These high quality polycarbonate slider windows are designed with the race driver in mind that wants an aero "Closed Window" for driving yet wants to be able to open the window. The slider is very high tech and works via a series of high powered magnets. These magnets ensure your windows stays put yet is easy to open or close while driving (Unlike the old school hand tighten type sliders). The opening at its full "Open" position measure 7 3/4" X 6 3/4". Priced and sold in pairs.