The Milwaukee SM600 Dissolved Oxygen meter is portable and designed for multiple applications such as school lab use, Aquaculture and wastewater treatment monitoring. It's reliable and accurate yet still very simple to use. The SM600 calibrates manually at two points, zero for the offset and 100% in air for the slope adjustment. The SM600 is used together with Milwaukee's MA840, a ruggedly designed polarographic D.O. probe which is conic shaped and features a temperature sensor for temperature compensated readings. Teflon membranes thread on and off for easy replacement in the field. The meter comes with probe, spare membranes, and oxygen electrolyte solution.