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 appropriate size by comparing with the dimensions shown. When in doubt, select a larger size as long as the core fits properly. Sound characteristics: This whistle produces a "boo, boo" sound, which differs from the actual turbo pressure relief valve sound of "h, bare". It is designed for entertainment purposes and mimics the general tone of turbo-like exhaust notes. Adds a sporty exhaust sound to your vehicle, enhancing driving experience with a unique and stylish touch. After installation, the exhaust sound resembles that of a turbocharged engine. Made of high-quality aluminum material, lightweight and durable. Universal fit design allows easy installation on most car tailpipes. Installation instructions: Place the turbo sound whistle inside the exhaust muffler with the larger opening facing inward. Easy to install within minutes. No tools required. 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. 2. Monitor display differences may result in slight color variations between the image and actual item. 3. Confirm your exhaust pipe size before purchase. The exhaust pipe inner diameter must be larger than the product's outer diameter for proper fitment.