ND filter allows the photographer to utilize a larger aperture that is at or below the diffraction limit. 
<br />Photographer can add a ND filter to limit light, and can then set the shutter speed according to the particular motion desired (blur of water movement, for example) and the aperture set as needed (small aperture for maximum sharpness or large aperture for narrow depth of field (subject in focus and background out of focus). 
<br />10 Stop exposure correction. 
<br />Suitable for dynamic screen, waterfalls, streams, waves, etc. 
<br />This filter is compatible with 77mm lenses. 
<br />Material: Optical glass 
<br />Diameter: 77mm, fits for the same size of screw lens 
<br />Item weight: 26g / 0.92oz 
<br />Package List:  
<br />1 * Filter
<br />Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.