Features: 1. Excellent quality: Made of high quality materials, safe and durable, not easy to wear. 2. Sound and sound: different specifications, sound and sound, crisp. 3. Easy installation: non-destructive installation, simple and convenient. 4. Wide range of applications: suitable for all types of cars, cars, motorcycles, racing cars, etc. Descriptions: 1. This is a whistle that simulates the sound of a turbine's pressure relief. The aluminum whistle, which is attached to the exhaust pipe, makes a sound through the airflow from the exhaust pipe. It is the sound of the flute. Specifications: Material: aluminum alloy Color: silver size: S is suitable for displacement of 1.0-1.6, exhaust pipe diameter 32-43 mm M is suitable for displacement of 1.6-2.0, exhaust pipe diameter is 37-48 mm L is suitable for 2.0-2.4 displacement, exhaust pipe diameter 44-55 mm XL is suitable for displacement above 2.4, exhaust pipe diameter is 56-85 mm Package Included: 1 x motorcycle car exhaust whistle Notes: Please allow 0-2mm error due to manual measurement, thanks for understanding. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Please understand, thank you!