Our patented technology allows for ferrous Iron (Fe+2) detection sensitivity of 0.02 ppm (mg/L) on the Iron Check test strip. This test promises to be an attractive alternative to wet chemical iron tests because there are no hazardous chemicals to mix and MSDS is not required. Quick results in minutes. And best of all, the Iron Test Strips are safe and easy to use for fast accurate results within the ranges of 0.0 to 5.0 ppm (mg/L), which permits the measurement of typical iron levels found in well and tap water. For visual detection of Total Iron (Fe+2/Fe+3) see WaterWorks Total Iron Pillows.