DigiPREP blocks are Teflon coated to resist aggressive corrovise attack for guaranteed long life in harsh laboratory environments. Seven sizes, ranging from 12 to 72 positions, offer the latest in graphite block digestion technology. All DigiPREP blocks are accepted and used in Environmental Protection Agency (E.P.A.) Office of Water Methods (i.e. 200.2, 200.7, 200.8, 200.9, 245.1 and 365.1) and Office of Solid Waste SW846 Methods (i.e. 3010a, 3020b, 3050b and 3060). Manufactured under ISO 9001:2008 certified quality program. CE, UL and CSA approved.