Designed for water quality experts, the Hach HQ440D Laboratory Multi-Meter is an advanced laboratory meter that takes the guesswork out of measurements. HQD meters connect with smart Intellical electrodes that automatically recognize the testing parameter, calibration history, and method settings to minimize errors and setup time. The advanced HQD Laboratory Meter is designed to withstand years of continuous lab use. HQD meters feature a simple user interface that does not require manuals or training to operate. The Intellical ISEF121 is a digital, combination fluoride ion selective electrode (ISE) with a non-refillable, single junction reference and built-in temperature sensor. The ISEF121 electrode is intended for laboratory use. The ISEF121 is ideal for measuring fluoride concentrations in drinking water, wastewater, and general water quality applications. The ISEF121’s solid-state sensor design eliminates membrane replacement and allows for dry storage of the ISE.