The Cokin X-Pro Filter System consists of a rectangular plastic filter holder with three slots (one for Cokin X-Pro rotating filters and two for rectangulars), a variety of optional adapter rings which can be locked into place by two retaining screws or rotated as well as many optical resin filters. The X-Pro System adapter rings cover sizes from 62-112mm, Hasselblad's B60, B70 and Rollei's B6. These filters are particularly suited for today's ultra-wide angle lenses (i.e. 17-35mm). Cokin X-Pro filters measure 130 x 170mm (W x H).