Neutral Density (ND) Filters allow you to reduce the amount of light reaching the sensor so that you can reduce shutter speed and get some motion effect. It is most commonly used to create motion blur in water and clouds. ND filters also allow you to use wide apertures in very bright conditions. Videographers use them to manage exposure so they can achieve the correct frame rates and depth-of-field.
 
The Full Neutral Density Kit includes:
 
ND2 (1 f-stop)
ND4 (2 f-stops)
ND8 (3 f-stops)
3 - filter cases
 
*Holder and Adapter rings sold separately