The Step Up feat says:
Benefit: Whenever an adjacent foe attempts to take a 5-foot step away from you, you may also make a 5-foot step as an immediate action so long as you end up adjacent to the foe that triggered this ability. If you take this step, you cannot take a 5-foot step during your next turn. If you take an action to move during your next turn, subtract 5 feet from your total movement.
Jaunt Boots say:
Three times per day, on command for 1 round when the wearer makes a 5-foot step, he can move up to 15 feet. This movement does not provoke attacks of opportunity.
So wearers with Step Up get a 15-foot jaunt whenever an adjacent foe makes a 5-foot adjust. I am reading that right aren't I?
Thanks for answers. However, on a related note: I'm not convinced that it's a standard action to activate. I know it says "on command" etc. but I think D'arandriel nailed it on this forum post when he said:
With all due respect to SKR, I can't imagine that the intent is to use a standard action to move 15 feet. It seems clear that the intent is to substitute 15 feet of movement instead of a 5 foot step up to 3 times per day, otherwise it's a completely useless item.
IMHO it's a Use Activated item with a command word:
Many use-activated items are objects that a character wears. Continually functioning items are practically always items that one wears. A few must simply be in the character's possession (meaning on his person). However, some items made for wearing must still be activated. Although this activation sometimes requires a command word (see above), usually it means mentally willing the activation to happen. The description of an item states whether a command word is needed in such a case.