We are driving to Key West from Jacksonville Florida and want to know about the sunpass. We got the following customer message, which is unclear since we just got a new transponder. Here is the state sent message: the records indicate you have recently been notified that one or more of your battery operated transponder has been selected for replacement at no cost to you. The transponder upgrade is necessary and mandatory for Florida Keys sunpass to continue growing and providing the highest level of customer service possible. Your Florida Keys sunpass battery operated transponder in Monroe County must be replaced in order to provide the best and most accurate level of service. If you choose not to take advantage of the no cost transponder program, your current transponder will eventually be de-activated. If you no longer use your Florida Keys sunpass transponder, please contact Key West sunpass today to deactivate your account. To view the types of transponders offered, go to selecting a transponder.