Features:Neutral density can be adjusted from ND2 to ND400, and it is easy to create different neutral density by rotating the ring.Apply slow shutter speed under strong sunlight exposure.Large aperture is available to create depth of field easily.Suitable for dynamic screen, waterfalls, streams, waves, etc.Index marks on the edge of filter for exact adjustment.Variable ND Filter is suitable for day-shooting while your camera is set in high Aperture and low shutter speed to create special effect.1) ND-2: Being able to lower 1 level aperture and 50% light quantity.2) ND-4: Being able to lower 2 levels aperture and 75% light quantity.3) ND-8: Being able to lower 3 levels aperture and 87.5% light quantity.4) ND-400: Being able to lower 9 levels aperture and light quantity, perfectly suitable for sun-shooting with long-exposure.(Note: The above neutral density levels are just some normal examples for reference, the real ND Scale is stepless and gradual.)Compatibility:Compatible with 55mm size lens.