These metal-backed thermometers have a V-shape design to help protect them from breaking. They have a glass tube but are mercury-free for safety so these are great for the classroom. Thermometers feature dual-scale temperature readings from -14-degrees F to 230-degrees F (increments of 2-degrees) and -33-degrees C to 110-degrees C (increments of 1-degree). Each thermometer is about 5-3/4” long. Set comes with 10 thermometers.