The Extech DO210 is a dissolved oxygen meter that measures dissolved oxygen in the range of 0 to 20.0 mg/l, oxygen content from 0 to 100.0% and temperature with ATC. This measuring device has adjustable compensation for altitude and salinity as well as minimum, maximum and data retention functions. The scope of delivery includes a dissolved oxygen sensor with membrane, a 1 m cable, two replacement membranes, electrolyte, 9 V battery and a soft protective bag.