Ray-Check precision I.Q.I.s rigidly conform to and exceed requirements of each code and MIL-spec. Lead figures identifying the penetrameter size and in the case of some MIL-specs the material, are affixed to the penetrameter. Each penetrameter is chemically etched identifying the material and specification. Sharp smooth edges with accurate, perfectly spaced, drilled and reamed holes, ultrasonically cleaned, give the technician every advantage in obtaining clear, well-defined images on the radiograph. All penetrameters are accompanied with certification and is traceable to the National Institute of Standards and Technology.