Sorry I have been so slack recently! I ordered some new two-cartridge Coleto's in my latest JetPens order, so I figured it was time for a peek. I really like how the Coleto ink cartridges write better that the regular Hi-Tec-C models. The only reason I can find is that the needle tip on the regular models is slightly longer than the Coleto models, and therefore has a little flex when I write. The Coleto cartridges don't seem to clog as much either. Oh well, maybe it's just me.