SPI feeler gage stock: 0.0060 inch thickness in a 1/2 inch wide x 25 feet long roll Type C 1095 high carbon steel; hardness rockwell C is 48 to 52 Useful for gauging clearances, narrow slots, spark plugs, and gear play Other applications include shimming in fixture and die work Marked every 6" with a line and thickness of stock Use SPI feeler gage stock for gaging clearances, narrow slots, spark plugs, and gear play. Also useful for shimming in fixture and die work. Marked every 6" with a line and the thickness of the stock. Crafted from Type C 1095 high carbon steel. RC of 48 to 52. Packaged in cardboard box.