Dual internal motor sensors gives better sensitivity for well-shielded motors External input for measuring mechanical contact closures when signal strength is low Auto-calibration of ON and OFF thresholds ensures reliable readings Compatible with HOBOware and HOBOware Pro software for logger setup, graphing and analysis The HOBO Motor On/Off data logger records motor on and off conditions within an AC magnetic field with its internal sensor, or mechanical contact closures from external sensing devices. This logger is ideal for tracking the usage & runtimes of motors, pumps, compressors, and other equipment. The HOBO UX90-004 Motor On/Off Logger is available in a standard 128 KB memory model (UX90-004) capable of 84,650 measurements and an expanded 512KB memory version (UX90-004M) capable of over 346,795 measurements.