The nibs
Solid 18k gold nibs from Schmidt or JOWO are standard. All JOWO #5 nibs fit. I can offer these in different materials and grindings, like 18k gold( EF, F, M, B), 14k gold (EF, F, M, B, also flexible versions), Steel (EF,F,M,B, 1.1, 1.4, semi flexible and full flexible versions).