The InvisiClean TDS Meter is a digital water testing meter. It is designed to test TDS (Total Dissolved Solids) measured in PPM (Parts Per Million), Temperature, and Electrical Conductivity. Use the TDS meter to test your tap water and drinking water. The TDS meter can be used for many applications such as drinking water, aquarium, hydroponic, swimming pools, spas, plants, and more. Included is a CR2032 battery and carrying case. Easy to read guide is on the back of the meter for use with our water pitcher filter.