Definitions | NIST Skip to main content An official website of the United States government Here’s how you know Here’s how you know Official websites use .gov A .gov website belongs to an official government organization in the United States. Secure .gov websites use HTTPS A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites. https://www.nist.gov/sri/definitions Search NIST Menu Close Publications What We Do All Topics Advanced communications Artificial intelligence Bioscience Buildings and construction Chemistry Cybersecurity and Privacy Electronics Energy Environment Fire Forensic science Health Information technology Infrastructure Manufacturing Materials Mathematics and statistics Metrology Nanotechnology Neutron research Performance excellence Physics Public safety Quantum information science Resilience Standards Transportation Labs & Major Programs Laboratories Communications Technology Laboratory Engineering Laboratory Information Technology Laboratory Material Measurement Laboratory Physical Measurement Laboratory User Facilities NIST Center for Neutron Research CNST NanoFab Research Test Beds Research Projects Tools & Instruments Major Programs CHIPS for America Initiative Congressionally Identified Project Program (CIPP) Manufacturing Extension Partnership (MEP) Manufacturing USA Office of Advanced Manufacturing Technology Partnerships Office Services & Resources Measurements and Standards Calibration Services Laboratory Accreditation (NVLAP) Quality System Standard Reference Materials (SRMs) Standard Reference Instruments (SRIs) Standards.gov Time Services Office of Weights and Measures Software Data Chemistry WebBook National Vulnerability Database Physical Reference Data Standard Reference Data (SRD) Storefront License & Patents Computer Security Resource Center (CSRC) NIST Research Library News & Events News Events Blogs NIST In Focus Feature Stories Awards Video Gallery Image Gallery Media Contacts About NIST About Us Leadership Organization Structure Budget & Planning Contact Us Visit Careers Student programs Work with NIST History NIST Digital Archives NIST Museum NIST and the Nobel Educational Resources Standard Reference Instruments Standard Reference Instruments Expand or Collapse SRI 6000 Series Programmable Josephson Voltage Standard (PJVS) SRI 6003 Series Portable Vacuum Standard SRI 6006 Precision Micro-machined Apertures SRI 6008 Ozone Standard Reference Photometer SRI 6011 Josephson Arbitrary Waveform Synthesizer SRI 6012 Precision Semiconductor Nanostructures SRI 6013 Standard Reference Optical Radiometer SRI 6014 Calibrated Reference Photovoltaic Cell Definitions Ordering Policies Expand or Collapse Required Ordering Information SRI Terms and Conditions Pricing Policies Sales and Customer Service Standard Reference Materials Definitions The NIST Standard Reference Instruments (SRIs) are designed to help the manufacturers and users of precision instruments achieve the highest possible levels of measurement quality and productivity. They directly link a customer's precision equipment and transfer standards to national and international measurement standards. These services are offered to public and private organizations and to individuals. NIST distributes and makes available for sale Standard Reference Instruments developed by NIST. SRIs are versions of an instrument used at NIST to realize and disseminate a measurement unit. An SRI offers the same or near levels of accuracy and precision achievable by the related NIST measurement service. Created December 19, 2022 Was this page helpful? HEADQUARTERS 100 Bureau Drive Gaithersburg, MD 20899 301-975-2000 Webmaster | Contact Us | Our Other Offices X.com Facebook LinkedIn Instagram YouTube Giphy RSS Feed Mailing List How are we doing? Feedback Site Privacy Accessibility Privacy Program Copyright & Disclaimers Vulnerability Disclosure No Fear Act Policy FOIA Environmental Policy Scientific Integrity Information Quality Standards Commerce.gov Science.gov USA.gov Vote.gov