Testing Range: 1-14 Full Range; Size: 55mmx9mm / 2'x0.35' (L*W) pH Color Chart Intervals: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 Widely applied to industrial chemical testing, science education, lab use, drinking water, swimming pool, spa, aquarium and classroom analytical chemistry. This paper does not apply to buffer solutions and very weak acid-base solution concentration lower than 0.01%. NOTE: Please note that solutions with a pH of 5.5 will result in a yellow colored test strip that resembles the original color of the dry strip. Store in a cool, dry place away from sunlight.