These rings are designed to allow curves to be machined, either directly or with a template. Each ring is used with the supplied bearing and security cap. The rings are made from high tensile alloy, so are light but also durable. A set of nine, these rings are all 16mm thick and use a 62mm OD bearing. The sizes included are 90, 95, 100, 105, 110, 115, 125 and 130mm. The set is suitable for a 30mm spindle. Supplied in a wooden storage box.