These high end scratch resistant polycarbonate windows are designed with the race driver in mind that wants an aerodynamically efficient "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" These windows are designed to fit in Cup or GT Racing "Race Doors" GT Racing Part #603A with window frames. Priced and sold in pairs.