The cokin w951 x pro filter kit contains a cokin x pro filter holder plus an x series 121m graduated grey nd filter and a 164 circular polarising filter the x121m graduated grey nd filter allows you to balance light intensity such as in bright contrasty landscapes where exposing for the foreground will produce a washed out sky while exposing for the sky will leave the foreground dark cokin grad nd filters are part clear part neutral density and allow the transition to be blended into the sc