Dry Erase, XY numbered axis, Graph Magnet will stick to any metal or magnetic surface, including whiteboards or chalkboards! The magnet measures 23" wide x 24" high and is ideal for demonstrations or at-the-board work. These graph magnets are easy to store when not in use. This graph features 20 x 20 squares that are 1" squares, with a numbered XY Axis. For use with dry erase markers. These are great for the math classroom! Use for demonstration purposes or small group activities.