Media playing device

A media playing device comprising:

• a housing including a middle portion and a cylindrical end portion, the cylindrical end portion shrinking radially relative to the middle portion to form a step and having an opening;
• a hollow turning knob with a cylindrical inside surface having two spaced contacting protrusions extending radially inwardly therefrom, the hollow turning knob being attached to the cylindrical end portion and the two contacting protrusions being located within the opening;
• a PCB disposed within the housing having an micro controller unit and at least one switch, the switch being contacted to activate;
• a side cover detachably attached to the cylindrical end portion cooperating with the step to limit an axial movement of the hollow turning knob;
• and
• attachment means on the cylindrical end portion and the side cover for detachably attaching the side cover to the housing,
• wherein, when the hollow turning knob is rotated to a position where one of the contacting protrusions contacts the switch, the switch is activated to send a signal to the micro controller unit, the micro controller unit executes an operation in response to the signal.