TF37 is a set of thread fit BBs that really fit 7 patterns by replacing the included parts. Installation tools are also included. Thread Fit BB (Thread Fit BB) is a new type of bottom bracket that screws on one and one piece sleeves from left to right to secure to the frame. Eliminates the sound problems associated with previous press-fit BBs and improves bearing life In addition, it increases the rigidity of the bottom bracket. The benefits of using ThreadFit BBs are easily replaceable without the need for press-fit BBs or removers for press-fit BBs. TBT specification for high rotational performance and durability This product is a genuine imported product with quality assurance, so you can use it with confidence (except parallel import goods). Product specifications, specifications, design, etc. may change without prior notice. Thank you for your understanding.