The HOBO Occupancy & Light data logger monitors room occupancy and indoor light changes to identify occupancy patterns and determine energy usage and potential savings. The HOBO UX90-006 Room Occupancy/Light Data Logger is available in a standard 128 KB memory model (UX90-006) capable of 84,650 measurements and an expanded 512KB memory version (UX90-006M) capable of over 346,795 measurements.