Ohaus 80850263 Wt Set(12), 500 mg-1 mg, ASTM 4, NVLAP Ohaus metric, American Society for Testing and Materials (ASTM) Class 4, stainless steel leaf-style calibration weight has a turned-up end to enable lifting, and is designed for calibration or for use with microbalances. The set of 12 weights is constructed of stainless steel for stability, resistance to corrosion, and low magnetic susceptibility. The weight meets ASTM E617, Class 4 specification for use as a reference standard for calibrating semi-analytic balances, and for student use. The set includes two each of the 200mg, 20mg, and 2mg weights, and one each of the 500mg, 100mg, 50mg, 10mg, 5mg, and 1mg weights, tweezers, and a covered box. The National Voluntary Laboratory Accreditation Program (NVLAP) accredits laboratories for compliance with ISO/IEC 17025 on the basis of their ability to meet the technical requirements set forth in NIST Handbook 150-2, and can provide accreditation to ANSI/NCSL Z540-1-1994. NVLAP calibrations and certifications meet all ISO, FDA, GMP, GLP, DOD, ANSI/NCSL Z540-1 and Nuclear requirements and are traceable to NIST. Procedures and processes used to generate this multi-page certificate, as well as its format and content, are prescribed by NVLAP. The document contains customer name & address, date of calibration, equipment and standards used in the calibration, accuracy class, true mass value (mass in a vacuum), As Found mass correction (for recalibration), As Left mass correction, uncertainty of measurement process (uncertainty to tolerance ratios are guaranteed), environmental conditions during test, construction and density of the weight, calibration procedure, and a statement of traceability to NIST. Mutual recognition arrangements include The International Laboratory Accreditation Cooperation (ILAC), The Asia Pacific Laboratory Accreditation Cooperation (APLAC) and The National Cooperation for Laboratory Accreditation (NACLA). Calibration weights are used to measure the weight or mass of an object using a balance or scale, or to calibrate other weights or instruments. Calibration weights can be certified or uncertified. Certified weights meet strict guidelines for accuracy and can usually be recertified. Certified weights are used in labs where a high degree of accuracy and repeatability is required. Uncertified weights are used where a lower degree of accuracy is required, including student laboratories, rough weighting operations, and measuring force. Hooked and slotted weights are often used to measure pressure, torque, and tensile strength, and to demonstrate basic laws of physics. Calibration weights differ from lab weights, which are general purpose weights used to hold an object in place, similar to a paperweight. Features: Metric, ASTM Class 4 leaf-style calibration weight set with turned-up end to enable lifting, for use with microbalances or calibrating weights, set of 12 Stainless steel construction for stability, resistance to corrosion, and low magnetic susceptibility Meets American Society for Testing and Materials (ASTM) E617, Class 4 specification for use as a reference standard for calibrating semi-analytic balances, and for student use Set of 12 weights includes two each of 200mg, 20mg, and 2mg weights, and one each of 500mg, 100mg, 50mg, 10mg, 5mg, and 1mg weights, tweezers, and covered box