Treasure Hunter in the Champion System, does it effect Safeboxes at all?

Aerius_Sygale

Does it add any chance of at least getting two items more often instead of just one so much of the time, or does it literally just effect "Chest" labeled locked containers only? Pretty sure the 50% more gold from chests effects safeboxes, so I have to ask to try get some solid confirmation one way or another, good or bad news. ^^;