This is a TDS sensor compatible with for ARDUINO, used to measure the TDS value of water. The TDS value can reflect the cleanliness of water and can be used for water quality testing in the fields of domestic water and hydroponics. TDS (TOTAL DISSOLVED SOLIDS), total dissolved solids, also known as the total amount of dissolved solids, indicates that there are milligrams of dissolved solids dissolved in 1 liter of water. Generally speaking, the higher the TDS value, the more dissolved substances are contained in the water, and the less clean the water is. Therefore, the size of the TDS value can be used as one of the bases for reflecting the cleanliness of water. Due to different batches, there may be differences in product appearance, color, and printed text, which will not affect the use. Color: Black Material: PCB Package Contents: 3 x TDS Meter Kit