How to say, “NO!” and live to tell about it? One powerful visual strategy is the universal NO symbol. These clear plastic symbols come in two sizes (25mm, 45mm) and stick to your laminated symbols to signal that the item is currently not available. The student can see the original icon through this symbol. Remove the symbol once the item is available. Re-use them as often as you need! You get 15 small (25mm) symbols, 15 medium (45mm) symbols.