Yellow fits all ![Smiley :)](https://www.eevblog.com/forum/Smileys/default/xsmiley.gif.pagespeed.ic.R8GFI-pF6f.png)
I have the system 4 esd set and they have coloured coded bits which is only interesting for pozidriv vs phillips.
FWIW, I've the System 4 ESD Drive-Loc kit (I love the ability to set the blade depth
![Evil >:D](https://www.eevblog.com/forum/Smileys/default/xevil.gif.pagespeed.ic.tdrs7Uj5gu.png)
). I also own a System 6 Drive-Loc kit I assembled (predominantly security bits). Aside from the larger bits, the handle I have is a non-ESD compliant version (again, red instead of yellow like the ).
Both of these also use color coded blade tips (downside is the enamel wears off rather quickly IME). It's very handy for Pozidrive v. Philips, as well as narrowing down hex sizes (i.e. SAE v. Metric).
In the end though, I find it's still more trial and error to get the right size.