|The polarizer simply slips over the nose of the LC/EF. Rotating the attachment varies the intensity of the light striking the target surface.
Adjusting the intensity will make the dot appear smaller by reducing the "halo" effect that is produced as the beam is scattered by the target surface and the diffraction pattern caused by passing a beam of light through a small opening.
Here is another way to look at it. When the laser is reflected from the target surface there is a primary "hot spot" at the center of the beam surrounded by a secondary ring of reduced intensity. By polarizing the beam we can begin to eliminate the secondary ring, making the primary hot spot easier to see.