These 1/8" thick clear Poly-carbonate quarter windows are direct replacements for the 987 Porsche Cayman with the addition of a NACA duct and fit in the original window mount. They are ideal in race car builds where you need to get additional air into the engine bay for cooling or the cabin for the driver. They are designed to fit a 2 1/4" hose. The NACA Duct and the window are not assembled. A 3M 2 sided tape comes with the kit for assembly or you can add fasteners in the NACA flange or both. Weight is less than 2 lbs per pair. Quarter windows are sold in pairs.