Precision Brand 19400 1/2" x 12" Flat Steel Feeler Gauge (0.011 Decimal/.279mm Thickness) 12pk. Precision Brand Feeler Gage is made from 1/2" wide spring steel stock, close grain C1095 high carbon steel. Hardened and tempered to RC 48-62. Material is ground and polished to precision tolerances. Used in manufacturing, tool & die, and maintenance operations wherever setting close spacing or checking extremely tight tolerances is required. Thicknesses are clearly etched every 6" in decimal and metric. Feeler Gage stock is packaged in 5" or 12" flat lengths, 25 feet coils and in convenient assortments. Also available in bulk quantities. Other sizes or thicknesses are available on special order. Meets FED-GGG-G-17C.