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 purchase. Choose the appropriate size based on the dimensions provided. When in doubt, select a slightly larger size if compatible. Sound characteristics: This device produces a "boo, boo" whistle sound during exhaust pressure release. Note that this is an imitation sound and may differ from the actual turbo relief valve sound. . Adds a sporty exhaust note to enhance driving experience. Gives the impression of a turbocharged engine when installed. Made of high-quality aluminum material, lightweight and durable. Universal fit design for easy installation on most vehicle exhaust tips. Installation: Insert the turbo sound whistle into the exhaust muffler with the larger opening facing inward. Installation can be completed within minutes. Package includes: 1 x Turbo Sound Whistle Specifications: Material: Aluminum Color options: Black, Blue, Gold, Red, Silver Note: 1. Please allow 1-2cm measurement deviation due to manual sizing. 2. Monitor display differences may result in slight color variations between image and actual item. 3. Confirm your exhaust pipe size before purchasing. The exhaust pipe inner diameter must be larger than the product’s outer diameter for proper fitment.