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. Choose the correct size based on the measurements provided. When in doubt, select a larger size as long as the core fits properly. Sound characteristics: This whistle produces a "boo, boo" sound effect, designed to simulate the turbo-like exhaust note. It is not an exact replica of a real turbo pressure relief valve sound but adds a sporty auditory enhancement for daily driving enjoyment. . Enhances your car's exhaust sound, giving it a more aggressive and unique tone, improving driving experience. After installation, the exhaust sound mimics that of a turbocharged vehicle. Made of high-quality aluminum material, lightweight and durable. Universal fit design, easy to install on most vehicle tailpipes. Installation: Insert the turbo sound whistle into the exhaust muffler with the larger opening facing inward. This device can be installed 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 measuring. 2. The actual color may vary slightly due to monitor display differences. 3. Confirm your exhaust pipe size before purchase. The exhaust pipe inner diameter must be larger than the products outer diameter for proper fitment.