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.