Set includes one base receiver and one sensor (ability to additional CWPIR sensors-Sold Separately).;Passive infrared (PIR) sensor is weatherproof and detects motion up to 30ft away and features adjustable sensitivity.;Base receiver detects signals from sensors up to a 1/2 mile away (in ideal situations).;Unique sound and light pattern on the base unit identifies which sensor has been triggered.;Easy to install, no wiring required. Base units uses AA batteries or included AC adapter.