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 chart and choose the correct fit. When in doubt, and provided the core fits, it is recommended to select a larger size. Sound characteristics: This whistle produces a "boo, boo" sound, which differs from the actual turbo blow-off valve sound. It is designed for entertainment purposes and mimics the general tone of a turbo release under acceleration. . Adds a sporty auditory effect to your vehicle, enhancing driving experience with a unique and stylish touch. After installation, the exhaust note will produce a whistle-like sound resembling that of a turbocharged engine during acceleration. Made of high-quality aluminum material, lightweight and durable. Universal design for easy installation on most vehicle exhaust tips. Installation tip: Insert the turbo sound whistle into the exhaust muffler with the larger opening facing inward. Easy to install in minutes without special tools. 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, actual product color may vary slightly from images. 3. Confirm your exhaust pipe's inner diameter before purchase. The exhaust pipe inner diameter must be larger than the whistle's outer diameter for proper fitment.