Description : This package includes a set of 10 pcs wheel bolts for changing the rollers. Made of high-quality iron with a coating on the connecting part, it is durable, strong and not easy to loosen. It is easy to install and can serve for a long time. Functions: Set of 10 screws for women and men for inline skating wheels. The 31mm roller bolt is the perfect replacement for the front wheel. The 36mm roller skating bolt is a perfect replacement for the rear wheel and brake bolt. Made of high-quality iron with a coating on the connecting part, it is durable, strong and not easy to loosen. Easy to install. Only suitable for skating shoes, requiring both male and female wheel bolts. Two 4mm hexagon wrenches on the double ends are required for installation. One hex key for clamping and one tool for getting the job done. Specifications: Material: iron Color: as shown in the picture Middle part length: 31mm, 36mm (optional) Middle part OD: approx. 6mm Upper hexagon socket diameter: 4mm Package weight : approx. 91g The package includes: 10 * Skating wheel bolts Difference in 1mm in length has no effect on the use. 2. Suitable for male and female nail rollers, not single head rollers.