https://habitium.com/ie/calibration-instruments/480170-calibration-block-with-15-mm-hole-for-thickness-weld-and-porosity-comparison-ideal-for-flaw-detectors-pce-instruments.htmlGB-480170Calibration block with 1.5 mm hole for thickness weld and porosity comparison ideal for flaw detectors PCE InstrumentsStandard for gauging thicknesses and bores.https://cdn.habitium.com/728368/calibration-block-with-15-mm-hole-for-thickness-weld-and-porosity-comparison-ideal-for-flaw-detectors-pce-instruments.jpg?sto=true&width=480487.57instockPCE Instruments531.24396.4835.5/Calibration Instruments