The Beltronics STI-R Radar Laser Detector is the high end of the radar detector game, running in the approximate price range of $1000 or up. This device is full of the best engineering and technology on the market, and will keep you in the clear when driving. It covers the wide range of radar use by police, even outside the United States, and can be set to scan for specific frequency types. 
It regards to its main features, one of the best is its ability to focus in on specific police radar bands. Other frequencies from devices such as garage door openers are filtered out, leaving the device to put its full concentration on the frequencies that matter. The Beltronics STI-R Radar Laser Detector is also programmable, as you can change the volume settings (reduced noise, automatic reduction in volume when nearer radar, etc.), or the sensitivity with which the device scans the frequencies. Additionally, the device is also able to be programmed for radar detection outside the US, such as Europe and Asia. This makes sure you have peace of mind when driving no matter where you are.
The market for the Beltronics STI-R is more for the experienced road driver who is used to using advanced radar detection. Its programmable features, which the multiple settings, require experience using many of its advanced features. Auto-scan is the best setting when driving at first, as you will get better results until you are used to how the device works. This way, you will have a successful drive with no worry about police radar.