Reference Weights, Mass Standards, Balance Calibration Weights, and Scale Weights & Test Weights adjusted to meet or exceed the tolerances for Troemner UltraClass, Class E0, Class 0, ASTM Class 1 to Class 7, NIST Class F, and OIML Class E1 to Class F2. Certified weights and weight sets are available with certificate traceable to NIST or ISO/IEC 17025 Accredited Certificate.