On the left is my collection of Promarkers . I have a few more but not enough to fill another case..... yet. I buy a few every so often to build up my collection.
This is a close up of the usual tips that come with the Promarkers, chisel one end and bullet shape on the other. On the left you can see the adapter and next to it the adapter attached tot he marker. It definitely widens the range of things you can do with them. The adapeter was less than £2 for a pack of 3 so it was very inexpensive. Now I've got to think of a project to use them on!!!