These 1/8" thick clear Poly-carbonate quarter windows are direct replacements for the 981 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 standard 3" hose. Weight is 2 lbs per pair. Quarter windows are sold in pairs.