So you just picked up a new 2015 Chris King TheadFit 24 Bottom Bracket, and you need one of its conversion kits for its new modular system. No problem. For riders who are running mountain bike cranks with a tapered 22 24mm spindle, such as certain SRAM, Bontrager, Truvativ, or Zinn cranks, and your bike has an 83mm wide BB shell, you're going to want Chris King Bottom Bracket Conversion Kit 15. The Kit slips onto the crank's spindle and then into the Chris King ThreadFit 24 Bottom Bracket on your bike. If you have any more questions about which CK conversion kit to use, please let us know and we'll help you out.