Lets you work on another city, anyones, for x amount of hours. Sell them for gems, ppl buy them and can use themselves (to work on multiple city on same device, you charge gems for hours of time, can also let your buddies work on your city for whatever reason, vacation or what not, can train for you...at time of buying you specify if it's for you, or you can type in a name and it gives to another player. What do you think Kabam? Helps us work on two accounts one device and makes you money paying the right.