The modern day optical mouse depends on scanning the surface and comparing that to the previous scan and by comparing the two images or patterns it can determine which way the mouse has moved. Now this happens very quickly but it is not perfect. Some times the mouse gets confused and cannot work out which way the mouse moved because either the images were too similar or a pattern on the surface managed to confuse the mouse. This is where the Everglide "Attack Optical" pad comes in.

Review Link : Techseekers