YSI 550A Dissolved Oxygen Meter - Powers On

Description

Up for sale, a YSI 550a dissolved oxygen meter.  This unit powers up and I can see the temperature reading change (when submerged in water).  Not sure how to test the other readout on the unit.  Sold AS-IS since I cannot guarantee correct operation but definitely not DOA.  Powers up normally and appears functional.
Cosmetics are fair, this unit shows normal wear.
US bidders/buyers only please.  This item will ship tracked and insured.