To make sure your disc brakes will always work smooth and flawless you have to make sure your disc is locked into place in a safe and reliable way. The CenterBlock is specially designed for centerlock hubs and 12 mm tru-axels. Due to the special design, there is no need to buy any extra tools. The CenterBlock can be attached with a normal Shimano cassette lockring tool (BTL-106S/107S).