Radio Shack Maximus Keyboard - Manual (Page 5)

Cleaning
Unplug before cleaning. Rub the shell with dry cloth. In case of significant
dirt accumulation use wet cleaning cloth for displays.
To clean the transparent key caps use special cleaning cloth for displays.
If dirt appeared inside the cap, you can use alcohol­containing liquids for
cleaning displays. Slightly moisten the cloth and clean the caps.
Do not use solvents, gasoline or alcohol to clean the keyboard as they can
spoil its surface.