So the magic item states after the fluff sentence: "They grant the wearer darkvision 120, as well as a +4 competence bonus on Perception checks and Survival checks made to track while underground."
Now, I just want to be sure - does the darkvision work when not underground? Does the Perception bonus work when not underground? Is it only the Survival bonus that applies underground, or that and the Perception check, or all three things?