A. This bicycle fork washer, also known as a headset spacer, is made of aluminum alloy and is sturdy and durable. B. It is available in a variety of specifications, including washers with different thicknesses such as 2 mm, 3 mm, 5 mm, 10 mm, 15 mm, and 20 mm, which can meet different fitting needs. Whether fine - tuning the height of the bicycle fork or making personalized adjustments, these washers of different specifications can be useful, helping cyclists create a more suitable riding experience. C. It has relatively strong adaptability and can be compatible with a variety of bicycle models. Whether it is a bicycle for daily commuting or a vehicle for professional cycling, it can fit well. D. It is a practical accessory for improving the performance and comfort of bicycles, which can bring more convenience and comfort to your riding.