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 ISENH3181 is a digital, combination gas-sensing ammonia ion selective electrode (ISE) with a replaceable membrane module, refillable outer body, double junction reference and built-in temperature sensor. The Intellical ISENH3181 electrode is intended for laboratory use. The ISENH3181 is ideal for measuring ammonia concentrations in wastewater, drinking water and general water quality applications.