There are two classes. The One Seat Class is for those competitors who only want to be judged from one seat. The Two Seat Class is for those competitors who want to be judged from two seats at the same time. If you are in an IASCA class that supports one seat judging, you will be allowed to choose which class you want in. If you are in an IASCA class that supports two seats judging, you will be only allowed to compete in the two seat class.