Wheeler-Rex 69012 Glass Tube Cutter
Brand: Wheeler-Rex
For .25-Inch thru .75-Inch (6–18mm) O.D. gauge glass, laboratory glass, and porcelain tube
Small enough to carry in your pocket and almost as simple to use as a pair of pliers
Just wrap the chain around the tube, and hook the nearest chain pin in the jaw
then a quick twist of the wrist, a slight squeeze of the handles, and pop