The REED R3530-Kit is a pen-style 4-in-1 meter that measures conductivity, total dissolved solids, salinity, and temperature on a dual LCD display, bundled with a conductivity standard solution for probe calibration. It offers data hold, min/max capture, automatic temperature compensation, and an IP57-rated housing for field use. A practical choice for water conditioning, aquarium care, wastewater checks, and beverage production.