The Tiffen 77mm Digital Neutral Density Filter Kit is a complete set of filters to help you get better shots in bright light as well as assisting you with some special effect images.
Neutral Density filters have several uses and offer the possibility to achieve otherwise unachievable results. They enable the shooter to adjust exposure without affecting color balance. ND filters appear gray and reduce the amount of light reaching the film.
Determining which neutral density filter yields ideal results for any given lighting situation takes knowledge, experience and a collection of such filters. Speaking generally, the 2-stop value (ND 0.6) effectively compensates average situations.

Neutral Density Filters Have Four Main Uses
To enable slow shutter speeds to be used, especially with high speed films, to record movement in subjects such as waterfalls, clouds, or cars
To decrease depth of field by allowing wider apertures to be used, which helps separate subjects from their background
To decrease the effective ISO of high speed film (above ISO 400) and allow it to be used outdoors in bright situation
To allow cine and video cameras (which have fixed shutter speeds) to film subjects such as snow, sand or other bright scenes which could cause overexposure