These pens seem to have cult following. I just received the the black roller in the mail and my list shows at least six more out there. Since this pen also comes in a fountain pen I may add one of them to the collection. Current collections that I am working on are the Rotring Core, Pentel side clickers and the glow in the dark Retro 51 pens. So much to do and so little time. Add them all to your collection.