The Mid-Level Chlorine test strip provides an easy way to accurately measure Free Chlorine in increments of 0, 25, 50, 100,and 200ppm. This test strip produces a distinct color change over the entire range from blue to brown to orange. This is a great alternative to our Chlorine Test Paper as it is a more accurate measurement of free chlorine. Our Chlorine test paper is only a semi-quantitative measurement, meaning it changes darker shades of one color (purple). This vial contains 100 strips.