Campbell Scientific CRS451V/CSR456V Vented Water-Level Recording Sensor
The Campbell Scientific CRS451V is a submersible datalogging sensor in a compact stainless-steel case which can be placed in remote sites for long periods. Long battery life and rugged construction mean you can trust the CRS451V to collect important data. Low cost and ease of use make it a good choice in a variety of applications. HydroSci software included.
The CRS456V is the same as this, but features a titanium case.