The description from MoMA Store:
This barrel-shaped desk clock has 12 sides, each with the name of two major cities. Altogether, the 24 cities represent the 24 Global Time Zones. To find the local time in another time zone, simply roll the clock so the city representing that time zone is on top. A great gift for business travelers and globetrotters.
Author of this interesting gadget is Charlotte van der Waals, [en:Dutch] Industrial Designer. And, she seems to be very "clock addicted", looking at another gallery of products from her: in particular, it seems that she loves to make "world universal clocks".
Prices? $74.00 if you are not a member of the MoMA Store, $66.60 for members.