Available in several diameters, adaptor ring will allow you to use your filter-holder on your favorite lens. The front diameter is usually printed on the lens, you can also refer its manual. Just screw the ring, insert the holder and some filters, then start shooting.
For Cokin P Series Holders P133 Yellow Y2 is twice the color density of Y1; requires 2 stops. Smooth-Edged Line of Transition Optical Resin CR39 Filter
For Cokin P Series Holders 8X Full is the same as P125S except that the tobacco covers the entire filter. Requires 3 stops. Enhances Gray or Colorless Sky Hard-Edged Line of Transition Optical Resin CR39 Filter
For Cokin P Series Holders the graduation extends to 3/4 of the filter. Requires 2 stops.Enhances Pink or Colorless Sky Smooth-Edged Line of Transition Optical Resin CR39 Filter