a pen-sized selection of various thickness strips of high quality metal, used to slide into the gap

A tool containing thin strips of metal of varying thicknesses. Used mainly by judges to determine measurements for the closest shoe and/or for determining if shoes are ringers.

A device with varying thicknesses for measuring the distance, or gap, between two surfaces. Feeler gauges are most often used to measure the gap on a spark plug or the gap in ignition points.