The 4001 Solinst Readout Unit (SRU) is an in-field device designed to take and display instant water level readings from a deployed Solinst datalogger. You can start and save a real-time monitoring session independent of the datalogger's internal logging. It has a built-in barometer, which provides the option of barometrically compensating the real-time readings. The SRU also functions as a data download and storage device. Saved log files can be transferred to a PC and viewed using Levelogger Software. The SRU also displays the datalogger's status, including battery level, memory, serial number, and firmware version.