Test Free Chlorine, Alkalinity, pH, Cyanuric Acid. 50 strips per bottle. The Insta-Test POOL 4 Plus pool & spa strip measures Free Chlorine 0-10 ppm, Total Alkalinity 0-240 ppm, pH 6.2-9.0, and Cyanuric Acid (Stabilizer) 0-250 ppm. This test strip is a dip-n-read strip with instant results. The Insta-Test POOL 4 Plus strip is ideal pool strip allowing the user to measure the most important test factors. The test strips are packaged in a waterproof PopTop bottle with a molded desiccant liner, which protects the strips from moisture and UV light.