The tool is composed of three steel parts: one rectangular bar and a pair of (opposing) uprights that slide along the bar and can be fixed in position by tightening screws beneath them. The bar is rectangular in section, 7/16-inch high and 3/16-inch wide. A small hole is pierced through one end (for hanging). It is calibrated in divisions of inches. Each upright can be fixed in position on the bar by twisting the screw beneath it. When a bar of type is placed between the two uprights, and they are tightened down, the size of the type can be read in the space on the bar.