Marumi® brand. DHG Variable ND2 to ND400 Neutral Density Filter. Steplessly rotates from ND2 to ND400 and anywhere in between Height = 9mm (not including rear threads) Pro quality filter. Made in Japan. Metal, double threaded frame to allow additional filters or hoods. 4 main uses: 1. Enables slower shutter speeds to be used. To display movement instead of freezing motion. Example, creative waterfall shots. 2. Decreases depth of field. Effecively blurring the background. 3. Reduces the amount of light reaching the sensor, but with no affect on color balance. Reduces light intensity, (sunshine, snow etc). 4. Allow video cameras to operate in bright light. Please note: To help prevent Vignetting the front filter ring is one size larger, ie 55mm.