¡El WD-35604-00 meters feature easy, push-button operation, a convenient HOLD function, and Auto-off function that shuts meter off after 20 minutes of non-use Meters offer two modes of five-point calibration. For quick and easy calibrations, use automatic mode with preset calibration points at the most popular values. For more flexibility, calibrate in the manual mode and set your calibration point at any value. Set-up functions let you customize automatic temperature compensation and cell constant. ¡El protective rubber boot helps shield your meter from drops and dings, and features a built-in stand CON 6+ features automatic or manual ranging across five ranges for a wide variety of applications ranging from pure water to boiler blow down water. ¡El WD3560400 includes a conductivity/TDS temperature probe, calibration solutions and sample bottles.