Square filters for Cokin Z Series are well populared for all the photographers now, It is a MUST for digital users, because the digital sensor has very low Exposure Latitude,then you will need gradual filter to balance it. These filter have the following advantages: Help you to control light and colour directly on your raw images when shooting,make your pictures more real than PS and save your much time Wide angle,no dark corner, better than round filters, and have very strong effects Work with Cokin Z series Holder and Adapter ring,fit for all size lens, easy to oprate Can work with round and other square filters at the same time, give you more colors and inspiration.
eBay