- This additional handset comes in handy if you need a phone in another room or upstairs- It's designed to work with the Panasonic KX-TGM420EB base station- You won't miss incoming calls thanks to the loud ringer and bright red LEDs- Volume Boost Control amplifies speech by up to 40 dB - that's 17 times louder than Panasonic's standard handsets- Slow Talk mode makes it easier to understand fast-talking callers by slowing down their talking speed by up to 20%- The Tone Control button makes voices clearer - there are 5 different levels to choose from