The Ohaus metric, stainless steel electronic balance calibration weight meets American Society for Testing and Materials (ASTM) Class 4 specifications, and is designed for use as a reference standard for calibrating other weights, or electronic balances and scales. The weight is constructed of stainless steel for stability, resistance to corrosion, and low magnetic susceptibility. It has a cylindrical shape with a groove for lifting. The weight meets ASTM E617, Class 4 specification for use as a reference standard for calibrating semi-analytic balances, and for student use. An optional National Voluntary Laboratory Accreditation Program (NVLAP) certificate ensures precision and traceability.

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.

Science education products incorporate applied math and science principles into classroom projects. Teachers in pre-K, elementary, and secondary classrooms use science education kits and products alongside science, technology, engineering, and math (STEM) curriculum to demonstrate STEM concepts and real-world applications through hands-on activities. Science education projects include a broad range of activities, such as practical experiments in engineering, aeronautics, robotics, energy, chemistry, physics, biology, and geology.

Ohaus manufactures scales and balances for laboratory, educational, retail, food, and jewelry applications. The company, founded in 1914, is headquartered in Parsippany, NJ.