Just to post some info on this watch. I paid $315 for mine and it is sad to see it up for $135!! Wish this was up when I bought mine 8 months ago.
Anyways, it is a kenetic watch, the button above the crown is meant to be pressed when the second hand reaches 12. It will then show you in 5/10/20/30 min increments how much charge is in the kenetic battery, take notice of the indicator strip on the inside. It is a pretty cool feature. I love the watch by the way, I would love it more if I could have found it for $135, an amazing price btw.
Good luck with the sale.