Compatibility and purpose Compatible with BC37x24 threads and designed specifically for BC1.37x24 specification threaded middle shafts. This tapping tool repairs and rethreads steel and aluminum alloy frames, enabling smooth installation without obstruction. Deep chip removal slots 8 deep chip removal slots facilitate the removal of short chips, reducing resistance and ensuring a smoother tapping operation. User friendly operation Drive side operation: clockwise removal with teeth inspection counterclockwise for quick checks by both beginners and experienced cyclists. Nondrive side inspection Nondrive side operation: inspect the teeth clockwise and remove counterclockwise for comprehensive bottom bracket maintenance. Use scenarios Scenario 1: Rebuild or stripped BC1.37x24 threads on a steel frame to restore a reliable bottom bracket fit. Scenario 2: Rethread worn aluminum alloy frame threads to enable proper installation of a bottom bracket. Scenario 3: On the road or in the workshop, perform drive side removal and inspection, then switch to the nondrive side to complete thread and retapping as needed.