[ymko]

Do you mean an option with:
max durability <=
max durability >=
?

That would do it =). AFAIK, the game only has very set levels of max durability, ie 40, 70, etc. So unless you want to future-proof the mod or use <= / >= for consistency, just a "max durability =" condition should do the trick.

There is a skill that increases max durability, i believe :P