The Insta-TEST® Peroxide (Biguanide Shock) strip measures peroxide levels from 0 to 90 ppm. This test strip is a dip-n-read strip with results in 10 seconds. Each bottle includes 25 test strips packaged in a waterproof PopTop bottle with a hinged cap. The bottle has a molded desiccant liner, which protects the strips from moisture and UV light. The Insta-TEST® Peroxide strip is ideal for a quick test in your water.