Alarm system with sensor pad * 20 x 30 * Sensor is under mattress and protected against incontinence * Weight of mattress keeps sensor pad in place to reduce false alarms * No sensor strip on mattress to compromise pressure relief and comfort * Available oversized 20 x 30 sensor provides reliable monitoring of restless sleepers * All UnderMattress sensor pads guaranteed for 90 days * BedPro Safety Alarm unit guaranteed for 1 full year * Operates on A/C Adapter (included) or Battery Power (1-9V battery included)