GiroDisc replacement rings are sold in pairs and include all the hardware necessary to replace both rings on a caliper. This makes it easy to order and install the rings and ensures that the correct parts are used. The rings also include new bolts, washers, and nuts, saving time and hassle as the necessary hardware does not need to be tracked separately. The only parts that need to be reused are the existing GiroDisc hats, which can save money and ensure the replacement rings fit properly. The replacement rings are only compatible with GiroDisc hats, ensuring they work properly and safely.