Handheld Oxygen Meter

The Lutron DO-5510HA oxygen meter can measure dissolved oxygen (0 to 20.0 mg/l), the amount of oxygen in the air (0 to 100%), as well as temperature (0 to 50°C). It comes with a polarographic probe that incorporates a temperature sensor. It features both built-in automatic  temperature compensation and salt and altitude compensation, which is adjustable. It records maximum, minimum, and average readings with a memory recall. There is also a data hold feature that allows you to freeze the last reading on the display until you are ready to move on.