According to the box, this tool is for 3/16, 1/4, 5/16, 3/8, 1/2, 5/8 OD Tubing. Has cadmium plated bars. The screw yoke is drop forged and it has a free-wheeling cone. Put out in the '50's by the General Hardware Manufacturing Co Inc, this is a quality tool which will continue to last for many years. Box is rather beat, but it is the original container. Tool in great shape, with some oxidation on the screw yoke lever, which I have not tried to clean. Still workable and waiting for that special someone to appreciate it.