Rosewill RM0830 User Manual page 3

For optimal performance, place the receiver at least 8 inches or 20 centimeters
away from other electrical devices, such as the computer, the computer monitor,
speakers or other external storage drives.
For a better transmission distance, avoid using this device on a metal plate or
desktop because a large surface of iron, aluminum, copper and other metal will act
as a shield or ground to the RF antenna of the mouse and receiver. Operating on a
metal surface may shorten the transmission distance.
If your notebook computer has a metal (contains Al or Mg) case, the metal
housing of the LCD panel will isolate partial radiation of the RF signal from the mouse.
This could possibly result in reducing the distance of transmission when you operate
the mouse right in front of the notebook and when the receiver is connected on the
back of the notebook. However, the RF mouse should work properly while you are
operating the mouse just beside your desktop computer.
Restorable Optical Wireless Mouse Page 3 of 11 2.2 Edition