Where certified magnification calibration standards are used for calibration of microscopes as part of ISO quality assurance procedures, protocols may stipulate that the standards used are recalibrated at fixed time intervals. We offer a recalibration service for Agar Scientific certified AGS1932 series of Silicon test specimens and the AGS170 SIRA test specimens where specimens are recertified by the original certifying body. This service is subject to an initial inspection to ensure specimens are in a satisfactory condition. Previously uncertified standards can be certified to conform to NPL standards.