F.U.N. Stands for Fluency and Understanding Numbers. Each of the 2 empty number line panels has a printed number line on one side and a number line with tick marks on the other side. 6 pull down suction cups enable mounting on most smooth surfaces such as whiteboards. 26 binder clips allow number line cards to be placed anywhere. 150 plastic links attach cards together at both the top and bottom to show equivalence. Includes user guide. Can be used with grade level sets sold separately that each include 25 blank write-on, wipe off cards for versatility.