The miniTROLL is the world's most advanced data logging probe. It is completely self-contained and features an internal data logger with a pressure/level and a temperature sensor. It is used by water professionals around the world to collect real-time information for analysis of both short- and long-term water level trends. Features: Smallest diameter at only 0.72 inches (18.3mm); Powerful onboard data logger - up to 1MB (440,000 data points); Linear, linear average, logarithmic, and event logging modes; User-replaceable AA batteries; High quality vented Quick-Connect cable (FEP or Polyurethane) - Fully detachable!; Ultimate 4-way level compensation including auto barometric compensation; Vented cable, Direct-Read cables OR suspension by low-cost wire; Networking and telemetry capable; Accuracy certified to NIST-traceable standards.