YSI 51B Oxygen Meter Yellow Spring Instrument With Probe

Description

For sale is a YSI 51B oxygen meter. It comes with the probe and the cord, and seem to be in good condition but I don't know how to test this. I did install batteries and each control seems to function but I am selling this as-is, untested. This may or may not need to be service to be fully functional. Sold as is and as pictured. No returns, Batteries not included. Thanks for looking.