Bearings are what allow the gears to rotate easily. They are usually created from bronze or brass, and so they healthy into races (or grooves) within the gearbox housing. Synchro rings have enamel on them that mesh While using the tooth about the gears, and so they even have friction https://titusvgmqx.boyblogguide.com/33109744/filter-gearbox-an-overview