CAS 7681-57-4 appears in our catalog under these names: Sodium metabisulfite, SO{2} 58.5% min , Sodium metabisulfite, ACS, 97% min , Sodium metabisulfite, 97% . Offered by: Thermo Scientific (Alfa Aesar). Available pack sizes: 500g, 2kg, 2.5kg, 10000g, 2500g.