The Chaya Kingpin is made of steel and designed to fit perfectly with the Chaya Zena Plates. The Kingpin is easy to install, so you can get back to having fun skating in no time. Each set consists of four pieces, which are enough to completely replace all four kingpins on your skates. If not used at once you can save some for a later service. The kingpin has a standard 3/8" thread, which is used on many roller skates.