The size of the product itself is closed. Since the product is to be unfolded, it is recommended that you buy a small one. If the product is still not suitable, you are advised to replace one of the exhaust pipes. Thank you for your cooperation. Features: Aluminum alloy material, solid installation, loud sound. The bigger of the size, the louder of the sound. Make your vehicle sound like a turbo vehicle with the turbo system or blow off valve. Applicable to all kinds of cars, motorcycles and racing cars. Easy to install on the car's tailpipe. Installation: 1. Loosen the bolt on the Turbo Sound Whistle. 2. Insert the the Turbo Sound Whistle into the tailpipe. 3. Tighten the bolt so as not to fall off while driving. Note: 1. Please make sure the tailpipe is big and long enough to contain the Turbo Sound Whistle. 2. Professional installation is always recommended, products damaged through self-installation will not be refunded. 3. Please check and re-tighten the bolt regularly. Specifications: Color: Silver Size: S, M, L, XL (Optional) Material: Aluminum Diameter: Approx. 3cm / 1.2in Length: Approx. 11cm / 4.3in Weight: 96g / 3.38oz Package List: 1 * Turbo Sound Whistle 1 * Small Spanner 1 * Screw