The System Sensor 4W-B is a 4-wire smoke detector and a member of System Sensor’s i3 Series of photoelectric smoke detectors. The 4W-B smoke detector works with most Honeywell alarm control panels including the VISTA-20P and VISTA-21iP as System Sensor is a subsidiary of Honeywell. However, you can also use the 4W-B smoke detector with other alarm control panels, but you should verify compatibility with the manufacturer of the alarm control panel first.