DESC: This radar detector is the size of a pack of cigarettes. The RMR-C430 radar jammer is a passive radar jammer. It has an outstanding jamming capability of 360 degrees, making your car completely invisible to the three radar bands X, K, Ka. The RMR-C430 has a 2-to-3 mile range. Once your vehicle is within 50 to 200 feet of the police radar, the radar has a chance of reading your speed. This is known as the "punch-Through". Drivers should adjust their speed accordingly. How it works RMR-C430's scrambling device blocks police radar and laser, making it virtually impossible to detect your vehicle's speed.