Specifications: Make your car sound like a turbo vehicle with the turbo system or blow off valve. Easy to install, no welding or drilling needed. Installation: 1. Loosen the screw on the turbo sound whistle. 2. Place the turbo sound whistle body inside the exhaust muffler with the larger opening facing the inside of the muffler. 3. Screw the screws on the turbo sound whistle to tighten the item so it doesn't fall off while driving. 4. Professional installation is always recommended. Type: Whistle Material: Stainless Steel S Size Diameter: 18mm/0.71", 102mm/4.02" (Approx.) M Size Diameter: 23mm/0.91", 102mm/4.02" (Approx.) Features: Lightweight, Durable, Useful, Easy to Install Notes: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Package Includes: 1 x Whistle