AirDefense's AirDefense Guard 4.0, AirMagnet's Air Magnet Distributed 4.0, Network Chemistry's Wireless Intrusion Prevention System 2.0, Network Instruments' Expert Observer 9.0 Console with Advanced Wireless Probe 9.0, Newbury Networks Wi-Fi Watchdog 3.0, and WildPackets AiroPeek NX 2.0.2 RFGrabber 1.1 are reviewed wireless overlay monitor products. AirMagnet is the editors' choice, and Wireless Intrusion Protection System is rated the best value. Wireless Intrusion Protection System 2.0 and AiroPeek omit support for user accounts with different access levels, and only Wi-Fi Watchdog 3.0 omits support for an import device list. Expert Observer does not provide configurable alarm-notification priorities, and Wireless Intrusion Protection lacks support for customizable alarm thresholds or settings. All the products provide on the fly security policy monitoring and MAC spoof detection alarms, but only AirDefense and Wi-Fi Watchdog 3.0 provide a device watch list. All but Wi-Fi Watchdog provide interference, channel crossover, or physical error detection for performance and configuration and policy monitoring. There are many other differences between the products, but AirMagnet Distributed 4.0 gets the highest scores overall, especially for security and policy monitoring, ease of installation, configuration, and operation, and performance and configuration policy monitoring.