What is the caster level of a wondrous item's effects?

Question

This is probably going to be a noob question but I can't find the answer in the core rule book.

With the wondrous item Hat of Disguise. It says you can cast the alter self spell and lasts for 10min/lvl and when you interact with somebody they make a will save to see if it is an illusion.

What I want to figure out is what determines the time limit and the will save check. Does it get determined on discovery/creation or does it increase by whomever uses it.

For example a 10th lvl rogue uses it and the will save is 10+1+10=21 will save. Or it was a created by a 6th lvl user and thus has a 10+1+6=107 will save while still being used by a 10th lvl rogue.

Answer 1

The Saving Throws of a magic item are determined by the creator of the item. There are some exceptions to this. Some feats and class abilities allow you to use your Caster Level instead of the Creator's.

Magic items produce spells or spell-like effects. For a saving throw against a spell or spell-like effect from a magic item, the DC is 10 + the level of the spell or effect + the ability modifier of the minimum ability score needed to cast that level of spell.

Staves are an exception to the rule. Treat the saving throw as if the wielder cast the spell, including caster level and all modifiers to save DCs.

Most item descriptions give saving throw DCs for various effects, particularly when the effect has no exact spell equivalent (making its level otherwise difficult to determine quickly).

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