Observing posted speed limits is obviously the most reliable method of avoiding costly speeding tickets. However, as most of us know, whether it is a lapse in attention, failure to see all posted signs, an instance of impatience, or a fear of being late, we all exceed the limit on occasion. For just these reasons, millions of drivers opt to invest in radar detectors to avoid the fines. Although radar detectors are banned in some countries and provinces, they are legal for passenger cars in all states in the US with the exception of Virginia and Washington DC.

There is a wide selection of radar detectors on the market and quite a bit of terminology to confuse first time buyers. However, the list of critical features that make a radar detector effective is rather short and once understood should make the purchasing decision a simple one.

The first choice a buyer will make is whether to purchase a corded, cordless, or remote unit radar detector. Corded radar detectors are the most common and can plug into a cigarette lighter or fuse box and are attached to the windshield. Buyers often choose corded radar detectors because they can be installed by the owner in seconds and don't require batteries. The other primary reason for choosing these particular devices is that they are capable of detecting all bands of radar signals.

Cordless radar detectors on the other hand are sometimes selected as they offer freedom from cords. Unfortunately, these devices are generally less effective however as they do not pick up all bands and have a more restricted range than corded models. Remote units are permanently mounted elsewhere on the car and are often selected as they cannot be seen by thieves or law enforcement. Remote devices are generally higher priced and require professional installation.

Since the purpose of a radar detector is to provide warning that drivers in the area are being monitored, it is important that the device pick up the bands being used and that the warning provided is sufficient. Buyers need to compare radar detectors as far as the distance at which they will sense a radar signal. Obviously, devices that sense a signal from a longer distance provide more warning and thus greater protection. To be functional, a radar detector should be able to pick up X, K, and Ka bands to assure that they will pick up the signals being used for monitoring purposes.

Another critical feature on a radar detector is how effective the alert is when a signal is picked up. The display should be easy to read, in daylight or at nighttime. Radar detectors often use LED but others use LCD displays. New buyers should determine which type of display best meets their personal needs. For instance, some prefer a text display but others feel the LCD display is difficult to see in the sunlight.

Some displays do a better job of indicating how strong a signal is so that the driver knows whether or not the threat of being detected is imminent. Obviously, having both a visual and auditory alert is important as a visual only alert could be missed.

Some radar detectors offer digital voice alerts versus an alarm only alert. Experienced radar detector owners would also recommend volume control and a mute button! Some devices will even offer an automated mute that is activated when driving in slower traffic when both speeding violations and monitoring are less likely.

Many radar detectors also offer features that allow the sensitivity to be adjusted to help reduce alerting the driver when radar signals are picked up from other sources: i.e. a "city mode" decreases sensitivity in urban areas where signals are picked up from security and other systems within buildings and equipment. The ability to filter out unrelated signals helps to reduce false warnings.

Some consumers also prefer to have a feature to shield them from having their device detected. Some devices shut down after alerting the driver and others use signals to shield them without shutting down.

Obviously, one of the newer methods of monitoring drivers are cameras at intersections with traffic lights. Beginning in 2007, some radar detectors will be offered which are capable of alerting drivers to these monitoring cameras and might be a valuable feature for some buyers.

A final, but very important feature that buyers will need to consider is whether or not the device they are considering offers laser detection. Certainly the use of laser guns by law enforcement has continued to increase and buyers have incomplete protection if their device monitors only radar signals. Laser is particularly useful to monitor drivers that are closer than what can be accurately measured by radar. This in turn means that drivers who are monitored by laser signals have even less time to react. Good laser protection requires placement of a head or sensor on the front of the car, usually in the grill, and additional sensors to provide 360 degree sensing to assure all signals can be picked up.

As with most electronics, there are radar detectors with all the bells and whistles, all of the features to assure maximum protection, and they may be well worth the investment for those drivers who hope to avoid expensive speeding tickets. For others however there are also very basic devices which provide a crucial warning but are easily affordable within almost any budget.