Chris King bottom bracket Fit Kits for DUB cranks are used with Chris King bottom brackets to ensure that cranks mate perfectly with bearings, extend product life, and reduce the potential for noise. Fit Kits will also allow you to use one bottom bracket with a wide array of cranks, if you happen to change you cranks in the future. FEATURES : Fit Kit 1 DUB A covers all DUB mountain fitments, as well as DUB road fitments with ThreadFit T47 bottom brackets For DUB mountain cranks with a 68mm BB shell you will need two 2.5mm cup spacers For DUB Super Boost + cranks you will need one additional spindle spacer kit