Smooth Polyester surface , Non-slip Rubber Bottom. The puzzle mat with rubber material makes the puzzle mat roll up less likely to leave creases to the finished or unfinished puzzle. Smooth polyester surface offers a waterproof base and maneuvers easily. Rubber bottom prevents puzzle saver from slipping. With 6 buttons type trays, press these adjacent buttons together and trays are ready to use. These trays help you sort the puzzle pieces by color or by pattern and are incredibly helpful for larger sized puzzles.