The mixer will process not only the desired input signal at fRF, but also all signals present at its inputs. There will be many mixer products (heterodynes). Most other signals produced by the mixer (such as due to stations at nearby frequencies) can be filtered out in the IF tuned amplifier; that gives the superheterodyne receiver its superior performance. However, if "f"LO is set to "f"RF + "f"IF, then an incoming radio signal at "f"LO + "f"IF will "also" produce a heterodyne at "f"IF; the frequency "f"LO + "f"IF is called the "image frequency" and must be rejected by the tuned circuits in the RF stage. The image frequency is 2 "f"IF higher (or lower) than the desired frequency "f"RF, so employing a higher IF frequency "f"IF increases the receiver's "image rejection" without requiring additional selectivity in the RF stage.