Replacement selector hub for later B type 3 synchro Minis. This component is incredibly important as it is responsible for smooth engagement into first and second gear, and also responsible for retaining the gear in selection. If you are hearing a grinding or having gears pop out, sadly it is almost guaranteed this part is damaged. Driving with a bad synchro will eventually result in damage to the gears themselves,  so if any noise is heard be sure to rebuild the box as soon as possible, or call us for an estimate. If you see any chipped or damaged selector teeth on either side, replace the unit.