These pens are an interesting bridge between a true fountain pen and a fiber
tipped pen. I used them when they were disposable, and as the Tradio. A
previous reviewer asked about cartridges - the pen tip is replaced along with
the ink storage area, it is like buying a whole new pen. If you were
enterprising enough, you could pull the nib and finned part out and refill with
ink, sort of like the pilot varsity pens. It promises to be potentially quite
messy, though, so be careful, and do it over a sink or something.