Hach SpecCheck Secondary Gel Standards Set, DPD Chlorine - LR, Chlorine Testing, Water Quality Standards, Accurate Chlorine Measurement, Laboratory Grade Chlorine Standards, 2635300;

Ready-to-use SpecCheck Secondary Standards Kits include four 10-mL (1-inch) sealed glass cells with a blank and three different standards within the typical testing range, instructions, plastic case and Certificate of Analysis. SpecCheck Standards are computer-formulated and have a two-year shelf life from date of manufacture.