These provide a complete self-contained measurement and recording system, for long-term data collection at remote sites, and options for remote telemetry.
The PS3100 is suitable for use in 2" (50mm) bores while the PS2100 is suitable for use in 1" (25mm) bores. The PS3100 can contain more battery capacity (9x Lithium AA) than the PS2100, hence its larger diameter.
Both models are available in gauge (vented to atmosphere to ensure the output isn't affected by barometric pressure changes) and have seven water level ranges available: 0-2.5m, 5m, 10m, 20m, 40m, 75m and 100m. Note that you'll need a closed vent system fitted to prevent moisture condensation in the vent tube.
Their overall accuracy is the same, at +/- 0.1% of full scale range over its operating temperature range of 0 - 50 degC.
The PS2100 will record 15 minute data for over a year and the PS3100 could record data every 5 minutes for the same period.
You can access the internal data logger via Smartcom software.