Selectable Frequencies Easily change the frequency on the handheld. Each handle mic requires a different frequency. Due to high cell phone signals, radio frequencies and wifi signals, microphones with selectable frequencies will help with the cutting in and out of sound. Just change the frequency on the mics. Strong Pickup and Echo Effect This plug and play set of microphones is able to assist your singing voice with strong pickup patterns and an echo effect. Open the battery cover and turn on the Echo effect. Echo is just an on or off selection. Turn it on if you would like an 'autotune' sound quality to your vocals. Turn the Echo off if you are doing speeches or sermons. Sound Bar Karaoke Fun These microphones work great in a bar or restaurant setting. But also will work for karaoke. Use the included AUX cable to connect the UHF-88MXR receiver to the AUX input of your Sound Bar. Bluetooth from your smart TV to the UHF-88MXR (select BT on the mic to activate pairing mode).