The pH System consists of a pH Electrode and pH Amplifier. The pH Amplifier contains the signal-conditioning circuitry. The pH Amplifier and pH Electrode are also available separately. Water inside the box will ruin it. Plastic tubing connects to a 3-way valve.
Older sensors have a metal valve, while newer sensors have a plastic valve.
I prefer the plastic valves - they are sturdy and very easy to control. The Radiation Monitor consists of a Geiger-Mueller tube and rate meter mounted in a small, rugged, plastic case. The unit is battery operated and can be used without a computer for measurement of alpha, beta, and gamma radiation from background sources. It can be used with a ULI and the Event Counter software to explore radiation statistics, measure the rate of nuclear decay, and monitor radon daughters. Unlike the barometer and pressure sensors, this sensor must be placed in the environment being measured.