Test strips for water quality measurement, easy to use, and results can be confirmed by color change. You can check the filter replacement timing of your water purifier based on the actual water quality. For reference, I've uploaded test strips comparing a Meisui water purifier used for 2 years (bottom) and tap water (top). It was found to be at an acceptable level, allowing me to extend the expensive filter replacement period. Since only the test strips are sold, they will be covered to prevent damage and, as they are sensitive to moisture, a desiccant will be included in a Ziploc-type bag and shipped via regular mail. A hard holder and desiccant will be included for protection during shipping and storage. - Product Name: Test Strips - Quantity: 2 - How to Use: Dip in water and measure by color change - Precautions: Important information regarding the water source is included - Measurement Range: Determines the presence and range of test elements Thank you for viewing.