Though the sensor packs were less sensitive than those found on higher-end beacons, they had a notably low mass, allowing for easy transport by sentients or pack animals. The sensor assembly contained twin motion sensor pods with visual scanning/recording functionality, analysis computers, and broadcast equipment. The upper sensor pod provided general scanning along with a long-range, wide-angle visual scanner and a motion sensor. In addition, it housed thermographic sensors and light detectors. The lower pod was responsible for more detailed scans and could scan and record with a visual scanner, an infrared scanner, and a thermal imaging unit. The lower pod also featured enhanced audio pickups whose feed could be added to the video recordings taken by the Vigilant. It had a range of 250 meters around it. To keep a 360° view of the surrounding terrain, the rotation joint (located just underneath the lower of the two pods) would spin the pods around at about four revolutions per minute. To provide the unit with power, even in remote locations, the Vigilant came equipped with retractable solar energy collectors. It could also be powered by a single energy cell at the base of its pole.
The Rebel Alliance used a number of SE-Vigilant units to keep watch over the frozen wastelands surrounding Echo Base. Luke Skywalker and Han Solo were setting up these sensors just before the Battle of Hoth.