the shifter moves the syncros back and forth which then slide over the gears… If you use a crappy shifter like me cough pilot cough, it doesn’t slide the syncros all the way over the gear and that wears down the teeth. Over time the teeth get so warn down the syncronizers don’t syncronize the gears and leads to gear grinding and not engaging gears. This means when you try to speed up your shifts, the syncro won’t allign properly and that gaer will jam, trust me, it’s super embarassing!LOL! I also had a problem with reverse popping out, which was the syncro not fully over the reverse gear combination. I can’t speak for the better brands but the design is better and a much more confident install.