Fluorescent Yellow Lumber Crayon #500 Wax-Based Marker. All-purpose marker for all surfaces. Marking range from -20 degree F to 150 degree F (-28 degree C to 66 degree C). 1/2" hex shape resists breakage and stays put without rolling onto the floor. The new fluorescent colors work well with the new computerized, scanner-equipped, cut-of I saws. #500 - harder crayon marks easily in hot climates. Lead-Free, Non-Toxic. Weather-Resistant, Fade-Resistant Colors.