Iron Test Strips 3-500ppm, 0-3-10-25-50-100-250-500ppmpH Buffer Powder Pillows for pH electrode calibration. Each powder pillow prepares 50 mL of fresh buffer solution. Color coded for easy identification (Blue). pH is 10. 01 0. 02 at 25C. Pack of 50 Powder Pillows Traceable to NIST standard reference materials Design for use with Hach and other meters. Product Type: Single Parameter Test Method: Test Strips Analyte Chemical: Iron NOTE: PLEASE ALLOW 2 3 DAYS FOR PACKING AND SHIPPING ON ALL TEST STRIPS