For easy identification, the size numbers are engraved into the feeler gauges The feeler gauges do not rust and are easy to open The edges of the feeler gauge set are made of steel and are polished full of bright metal structure, specially treated, smooth and do not hurt your hand Feeler gauges for valves fold into a steel housing with a thumb screw, are easy to carry, convenient to carry and safe to store The set of conical feeler gauges is made of hardened and polished steel for time and accurate use, Manufacturer: OSNIYAW