What does the four-speed DPI of Fuller mouse mean?

The mouse dpi (resolution) refers to the positioning accuracy of the mouse, and the unit is DPI or cpi, which refers to the maximum amount of information that can be accurately positioned per inch when the mouse moves.

In fact, at the beginning of the exercise, the mouse with 800cpi responded faster than the mouse with 400cpi.

If you suddenly change the resolution with the customary DPI, you will be very unaccustomed, because the mouse movement speed changes greatly.