You will most likely have a short period of time to decide.
Your option itself may not be traded! It will be offered to another share holder if you choose not to exercise it.
Guesstimate...Im figuring the option will be about 25% to %30 of what I currently own. There is currently 40mil shares out. 33 mil float. They are trying to raise 5 mil so it seems they will be offering 10 mil shares @.50 to current holders. All of this is just a guess based on whats been released so far.
The vast majority of all cosi shares are owned by insiders and institutions according to yahoo fin.