The ring adapter and filter holder is attaches to lens to hold both square and round filters, as well as optional modular accessories such as the Cokin Modular Hood & Coupling Ring.
67mm cokin filter-holder which can be precisely adjusted, coupled to the lens by means of a screw-in adaptor ring. The filter-holder has four grooves. One takes round filters,which can be rotated in the groove. The three others take squarefilters which can be adjusted up or down at will.

Lens Pink Color Conversion Filter for Cokin P seriesUS$7.66 US$5.66 |
Perfect! The adapting ring is made in a sort of metal, the holder is in very good plastic, so it's very sturdy! The filters fits nicely and securely in the holder. Very good.
El soporte y el anillo encajan bien. La rosca del anillo enrosca bien en el filtro de la lente. Sería mejor que vendieran sólo los anillos de diferentes diámetros; no necesito un nuevo soporte de plástico cada vez que compro uno.
Adapter ring and filter holder ok. I have three different rings, but I don't need three filter holders. It would be nice, and cheaper, to buy only the rings.
Thanks.
Es bastante barato pero es de plastico