They are made from 1/2″ wide, C1095 close grain, high carbon spring steel. Material is ground and polished to precision tolerances. Steel feeler gage is used in most general maintenance and tool and die applications. Thickness is marked every 6″ in metric and decimal. Measures 1/2″ wide by 5″ long. Precision Brand® Feeler Gage is used in manufacturing and maintenance operations wherever setting close spacing or checking extremely tight tolerances is required.