Extech EC400 Exstik Digital Handheld Conductivity Meter is designed with 3 ranges of measurements from tap water to wastewater and any aqueous solution requiring conductivity, TDS, or salinity measurements. The Extech EC400 features an adjustable conductivity to TDS ratio factor from 0.4 to 1.0 to easily calculate the TDS value, automatic temperature compensation, and an on-board memory capable of storing up to 25 labeled readings.