For precision weighing, select from either electronic or precision analytical balance masses. Electronic balance masses are cylindrical shaped for easy stacking on balance weighing pans. Precision analytical masses feature two-piece construction and consist of a special austenitic alloy for high precision and stability. Both groups of masses meet ASTM Class 1 or ASTM Class 4 standards, and are available with either a *NVLAP Lab Code 105013-0 (National Voluntary Laboratory Accreditation Program) or traceable certificate. For commercial applications, choose an NIST Class F weight. Use the descriptions below to select the best calibration class for your application.