uses a cord for a power source and is the most popular. 
They effortlessly plug into the cigarette lighter adapter or fuse box and remain on at all times, while the key is turned. Because they remain on continuously, they have a 100% better chance to detect the newer "POP Radar" used in many radar guns.Cordless radar detectors: This type of radar detector uses batteries, and sometimes solar power. Without cords, they'll provide a cleaner installation. However, in order for the batteries to last as long as possible, these radar detectors will turn themselves on/off in milliseconds which may shorten their range of detection.
Remote-mount radar detectors: Going "invisible" - Not only permanently mounted to your vehicle and hidden away from thieves, but out of view from law enforcement. 
Remote-mount radar detectors are not as commonly used due to their lack of portability, however, give you the true feeling of "stealth mode".
Radar Detector Features
Most cheap radar laser detectors are designed to detect the most commonly and uncommonly used radar bands, but may also detect laser, too.
City mode: When city mode is turned on, radar detectors will become less sensitive and decrease their range. This is because radar detectors "sense" garage door openers, intruder alarms and automatic doors using radar technology.
Laser detection: There are many radar detectors equipped with a laser sensor that detects beams in front of your vehicle, but not on your sides or behind. Newer models may include 360 degree laser detection, which assures you more coverage since there are a several sensors to give you protection from all sides, including the rear.
Spectre and VG-2 protection: These shielding features are important since they inform the driver if police have a Radar Detector Detector (RDD). Spectre is considered as a more sophisticated RDD technology and would most likely be used in states where radar detectors are illegal. 
Some detector models provide Stealth, a kind of protection that warns the driver and turns off the radar detector. More advanced models may provide what is known as "Invisible", a kind of protection that shields the radar detectors from Spectre, VG-2 or both, as they simply continue working without being traced.
Digital voice alert: Radar laser detectors can be equipped with digital voice alerts that will inform the driver of any laser, beam, or pulse that they were able to detect. Instead of looking at the radar detector every time it "beeps", the driver can now keep their eyes on the road.Radar Guns Vs. Radar Detectors... The History
In the 1950s, police officers were introduced to a new radar technology that allowed them to capture the speed of motorists traveling towards them from a distance away. 
As far as speeding was concerned, police officers had the "strong hand" for roughly 20 years.
In the early 1970s, a man by the name of Dale Smith received a speeding ticket he felt was unfair. He soon developed a device called a Fuzzbuster, which gave drivers an alert if any radar gun systems were targeting their vehicle. The Fuzzbuster detected radio signals sent out on the band of police radar guns. It produced a high-pitched sound and lit up when the radar was detected. Dale Smith decided to start his own company to manufacture radar detectors, and they became a wide-spread popularity among motorists.
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Radar detectors will deliver a higher level of comfort while driving and also drastically reduce the chance of receiving a citation, better known as a speeding ticket. Laws vary from state to state - It's best to know if it's legal or not to use a radar detector in your vehicle.
