Reagent-delivery style strip gives results within 15 seconds. Testing is accurate and reliable double duty, high-density outer shell combined with desiccant sleeve ensures less moisture and light. Desiccant liner stays in the vial and can't fall onto wet hands. Connected cap won't fall into water or onto wet deck leak proof, airtight seal meets USDA and FDA requirements. Desiccant sleeve is double the industry standard for moisture protection (6g)High Density Polypropylene Plastics (HDPP) protect strips better than HDPE bottles Hinge. Guarantee rated for over 1,000 openings. 30-month shelf life which means you can stock up. Works on pools and spas of all sizes.