Description General description This certified reference material (CRM) is produced and certified in accordance with ISO/IEC 17025 and ISO 17034. This CRM is traceable to SI unit kg and measured against primary material from an NMI, e.g. NIST. Certified content incl. uncertainty and expiry date are given on the certificate. Download your certificate at: http://www.sigma-aldrich.com. Legal Information TraceCERT is a registered trademark of Sigma-Aldrich Co. LLC