Leak Spot Detector is used to detect liquid in a specific spot, such as, inside of a condensation drip pan. The Spot Detector features a small enclosure with adjustable probes. It can be attached to a flat surface and submerged in water. Leak Spot Detector attaches to one of the eight digital inputs on the RIM-750. You can use up to four Leak Spot Detectors with RIM-750; however, each Leak Spot Detector counts as 50 feet (15.2 meters) of Sensor Rope and will reduce the total length of Leak Detection Sensor Rope supported by the RIM-750 by 50 feet (15.2 meters). For example, you could use two Leak Spot Detectors and 100 feet (30.4 meters) of Leak Detection Sensor Rope.