Datalogging Relative Humidity Temperature PenRecords up to 32,000 data points that can be downloaded by plugging the pen directly into a USB port no cradle or cable necessary. Data logging can be programmed to begin immediately, at a predetermined time, activated by the unit's push button, or to continually roll over after a set number of data points. Green and red led lights indicate data logging and alarms. Comes with software, 3. 6V AA battery (3. 6V ER14250), tripod screw and a wrist strap.