1. This mountain bike stem spacer is designed for road bikes. It is made of carbon fiber, which can bring a certain improvement to your cycling experience. 2. As a spacer for the fork head tube riser, it is suitable for the bicycle head and can effectively adjust the height of the handlebar to meet the needs of different riding postures, making your cycling more comfortable. 3. In terms of specifications, there are multiple options. There is a 5-piece set that includes one piece each of 3mm, 5mm, 10mm, 15mm, and 20mm spacers, and a 4-piece set that includes one piece each of 5mm, 10mm, 15mm, and 20mm spacers. Of course, there are also single spacers of 3mm, 5mm, 10mm, 15mm, and 20mm available. You can choose flexibly according to your actual needs. 4. Whether you are an everyday cycling enthusiast or a professional cyclist, this bicycle stem spacer can fit your bike well and help you enjoy a more enjoyable cycling journey.