This is a unique tool, shaped as wood tongs encased in a brass band. When the tongs are closed the circumference of the band grows smaller. As the tongs close, one arm moves over a brass scale. The measurements on the scale are in centimeters and correlate to hat sizes written below on the same scale. For instance a measurement of 55 centimeters gives you hat size 4 ½. A milliner/hat maker would use this tool inside a hat band to measure its size