WattStopper's Neutral Sense Technology Complies with 2011 NEC requirements Zero-crossing for long relay life Vandal resistant lens combines precise coverage with durability Selectable walk-through mode turns lights off three minutes after the room is initially occupied if no motion is detected after the first 30 seconds Test mode allows quick and easy adjustments Selectable audible and/or visual alerts for impending shutoff LED indicates occupancy detection In automatic mode.