HERE's my thread from about 3 years ago.
I'll go back through that post and try to upload images to make the considerably long text actually make some sense.
(the images were on the old image library which got nuked with a site upgrade a long time ago .. so I have to try to remember which image goes where too).
considering the cheapness of these cheapy coloured grads, they worked remarkably well.
FWIW: the only reason I don't use them any more is that I had to upgrade to larger filters from Cokin P series to Lee's 100mm sized filters.