These jockey wheels are made of high-quality aluminum alloy, which is durable and wear-resistant. The bearing is made of high-quality steel, which has a long service life and is not easy to deform. The surface is treated with black anodizing, which has good corrosion resistance and is not easy to fade. The installation is simple and convenient, and it is suitable for most mountain bikes, road bikes, and BMX bikes. The package includes 2 pieces of jockey wheels, which are sufficient for your replacement needs.