Kitagawa Gas Detector Tube change colors when chemical reagnets filled in a glass tube react with sampled target gas through the tube. The stain created is proportional in length to the concentration of the target gas, so the concentration is read directly off the printed scale on the tube.
A Shatterproof Detector Tube has 2-layer of films to protect from a breakage. Even if broken, the inside reagents do not scatter.
For more information, please see Data Sheet and Kitagawa Brochure