Specification: Na2S2O3. 5H2O: 99 % Min Water Insoluble: 0.01 % Max Na2S: 0.001 % Max Iron content: 0.002 % Max PH value: 6.5-9.5 Appearance: Transparent clava Cargos in 25kg or 50lb PP woven bag, kraft bag, PE bag, 1000kg or 2000lb super sack.