allen wrench for bridge?

[oh_the_blood]

what kind do i use to adjust the action?

[ez_willis]

What kind or what size?

There's only one kind of allen wrench.

As far as size goes, it'll be the one that fits.

[oh_the_blood]

what size? sorry.

[Dani Pace]

If you mean the little ones on the saddles, you may have to go to a music store to find one. They are really small so a standard size set of hex wrenches may not have one small enough to fit.

[arcaxis]

As far as size, Allen wrenches come in two flavors, SAE (fractional inches) or Metric. Make sure what ever you get fits snuggly with no play. They aren't particularly expensive and a set of both to have in the toolbox is handy.

[Scinx]

Depends on the saddle. Mine (Graphtech Strat) uses a .050" hex key

[Clive Hugh]

A general rule of thumb. If it was made in the USA it will be SAE or "imperial" referring to inches, if it was made in Asia or Europe it will be metric. There are of course exceptions to every rule but that one is a good start.