These are GT Racing's replicas of the Porsche factory's 911R window. These high quality windows are vacuum formed and precision CNC milled using clear impact resistant PETG with open louvers and water drip pan. They are designed with a flange that allows the window to raise up from the bare window opening with no frame just like the factory. These windows are sold in pairs. Tech Tip: The Porsche factory glued this window in using clear silicone. Sold and priced in pairs.