Neutral density filters play an important role for filmmakers and photographers because they allow you to precisely control the amount of light passing through the lens for greater creative control over exposure. For filmmakers, this means shutter speeds that match your frame-rate while maintaining the depth-of-field you want. For photographers, it means you can reach longer exposures or achieve a shallow depth-of-field in bright sunlight.
Stack ND filters to get different stops (ie. a 3-stop on top of a 6-stop is equivalent to a 9-stop filter)
Lightweight and made of top of the line materials
Allows you to control light for better photos and videos