The Broadband R309 operates at any frequency between 25 kHz to 45 kHz and 130 kHz to 210 kHz. Adjusting the frequency allows you to change the R309’s beam width and depth capabilities. For example if you are bottom fishing in 61 m (200 ft) of water, the narrow high frequency beam will display extreme bottom detail and fish holding tight to structure. If you are tuna or marlin fishing in deep blue water, the wider, low frequency beam will not only give deep-water bottom detail, but more importantly show you more of what is around your vessel, including bait which may attract game fish. Because the R309 has a bandwidth that covers a continuous frequency spectrum, next generation fish finders utilizing Furuno Free Synthesizer (FFS) technology can be made “tunable”, so fishermen can “dial-in” the best frequency for the target fish species or conditions.