It is adustable ND FIlter . Apply slow shutter speed under strong sunlight exposure, large aperture is available to create depth of field easily. These filters are double threaded allowing additional filters or accessories to be mounted one over the other. Made of high quality optical materials. The number indicates the fraction by which light is reduced; for example, ND2 cuts the light entering the lens by 1/2, ND4 by 1/4. Diametre: 40.5mm Applicable : All the camera lens which has 40.5 mm diametre Neutral Density filters are used to reduce the quantity of light that reaches the sensor of the camera. They allow to decrease the shutter speed in order to achieve motion blur (waterfalls, ocean, clouds...) and/or to reduce depth of field in very bright conditions. As they are "neutral", ND filters do not affect color rendition. With Variable Density Neutral filters, users can select the intensity from ND2 (1 f-stop) to ND400 (9+ f-stops) by rotating the front ring. Brand No Brand SKU 101026380_NP-1021566326 Filter Attachment Type Screw-On Water Resistant Yes