The ProOptic Digital Essentials Filter Kit Inludes: Circular Polarizer (CPL) Filter Reduces glare and enhances color by selectively cancelling the amount of reflected polarized lightwaves caused by a wide variety of objects, such as glass from buildings, cars and vessels, the sky and clouds, foliage, precious gems, pavement, sand, snow and water. In landscape photography, a CPL can piercehaze revealing dramatic vistas, increase tone and color vibrancy plus give the illusion of depth. By carefully rotating the rings of the filter, you can observe the cancellation effect in the viewfinder tothe degree that you desire. The filter has no effect on metallic substances as they do not reflect polarized light and little effect on flash as the light source must be polarized as well. The Filter Factor varies from 1.25x to 2x depending on the strength of effect. Neutral Density (ND2x) Filter Neutral Density filters evenly reduce the amount of light passing thru the lens without effecting color. They are ideal for situations when a narrow depth is field is needed and the lighting is too bright to allow for large apertures with your chosen shutter speed. Likewise, they allow for slower shutter speeds when you want to record objects in motion. ND filters are a must have tool for filmmakers as well. The ND Filter also lets you use high speed films in bright light, in case you haven't gone digital yet. The Filter Factor is 2x - reduces the light one f/stop.