Rear axle conversion kits convert your hub to fit a new axle measurement or for a new group set. All DT Swiss hubs can be converted. DT 12 x 142mm and 12 x 148mm rear hubs use the same end caps Also used for 12 x 157mm spacing Not SCS compatible End caps do not convert non-Boost hubs to Boost 148mm spacing . DT 142x12mm and 148x12mm hubs simply share the same end caps