YEONHWA M TECH XP-100D User Manual page 10

5.5 CH/Menu UP/Down Button
"CH / MENU UP" and "CH / MENU Down" are to change channels and in the menu entry mode, it
is select the UP / Down of the Menu.
5.6 EAR/MIC Jack
Accessory connector is used to connect external speaker Mic, and headset, etc.
Please close the cover when nothing is connected.