Small/applicable displacement: 1.1-1.6L, applicable exhaust pipe caliber: 32-43mm Medium/applicable displacement: 1.6-2.0L, applicable exhaust pipe caliber: 37-48mm Large/applicable displacement: 2.0-2.4L, applicable exhaust pipe caliber: 44-55mm Plus/applicable displacement: 2.4L and above, applicable exhaust pipe caliber: 56-85mm Size selection guide: Please measure the inner diameter of your vehicle's exhaust pipe before purchasing. Compare with the size chart and select the appropriate size. When in doubt, choose a larger size if the core fits properly. Sound characteristics: This whistle produces a "boo, boo" sound effect, which differs from the actual turbo pressure relief valve sound. It is designed for entertainment purposes and mimics the general tone of turbo exhaust sounds. 100% brand new and high quality. Adds a sporty exhaust note to your vehicle, enhancing driving experience with a unique and stylish sound. After installation, the exhaust emits a sound similar to that of a turbocharged engine. Made of high-quality aluminum material, lightweight and durable. Universal fit design, easy to install on the car's tailpipe. Install the turbo sound whistle inside the exhaust muffler with the larger opening facing inward. Simple installation process, can be completed within minutes. Package Includes: 1 x Turbo Sound Whistle Specifications: Material: Aluminum Color: Black / Blue / Gold / Red / Silver Note: 1. Please allow 1-2cm measurement deviation due to manual measurement. Ensure you are comfortable with this range before ordering. 2. Due to differences in monitor displays, the actual color may vary slightly from the images shown. 3. Confirm your exhaust pipe size before purchase. The exhaust pipe inner diameter must be larger than the product's outer diameter for proper installation.