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 About size selection: Please measure the inner diameter of your vehicle's exhaust pipe first. Compare with the sizing diagram and select the correct fit. When in doubt and core compatibility is confirmed, opt for a larger size. Sound characteristics: This whistle produces a "boo, boo" sound, which differs from the real turbo pressure relief valve sound. It is designed for entertainment purposes and not an exact replica of actual turbo sounds. . Adds a sporty exhaust note to your vehicle, enhancing driving experience. After installation, the exhaust sound mimics that of a turbocharged engine. Made of high-quality aluminum, lightweight and durable. Universal fit, easy to install on the car's tailpipe. Install the turbo sound whistle inside the exhaust muffler with the larger opening facing inward. Easy to install 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. Confirm sizing before ordering. 2. Due to monitor differences, the actual color may vary slightly from the image. 3. Confirm your exhaust pipe size before purchase. The exhaust pipe inner diameter must be larger than the product size for proper fitment.