The no. 6 flex nib from Fountain Pen Revolution fits in a Penbbs 456, this one in the absinthe material. The ebonite feed was shaved slightly to fit the plastic section housing. I modified this nib with wing scallops along the lines of the flex nib experiments in the thread below. FPR now sells these ultra flex nibs with wing scallops included. The ink is Diamine umber, and the paper is from MUJI.