Originally Posted by
aggiegrads
Nearly all derailleur screws are JIS. Most shops use JIS drivers, but most home mechanics don’t know that there is a difference.
Just to add that JIS = Japanese Industrial Standard. Anything manufactured in Asian countries as far as I know uses this standard. In any case I used the non JIS screwdrivers most of my 50+ years of wrenching with the occasional stripping of JIS heads, purchased some JIS tools about 10 years ago and what a difference. These really lock into the screw heads and allow much more torque to be used without stripping and are especially valuable for small bike screws.
JIS vs Phillips screwdrivers and Where to buy a JIS screwdriver. | Helping you work smarter not harder (rtstools.com)