Almost all Bauer holders have a 3-digit number on the back corner of the holder. Simply flip one of your skates over and locate the 3-digit number. The indicated number will tell you the size of the runners that you will need. If your holders do not have a 3-digit number, use our sizing charts to find your corresponding holder model. From there, look to the right until you locate your skate size. The 3-digit number below the indicated skate size will be the size of the runners that will fit your skates.