Couldn't live without the Frixon pens I learned about here...also the Bohn white mechanical...Got mine on Amazon prime where they have a package with several and several replacement cartridges included...have to wade through a lot of different offers to find the best packaging deal. Only problem is I have forgotten and pressed, wiped out my markings and had to start over...there were some bad words said there...LOL Also use regular chalk in a big, hand held pencil sharpener...can get a tiny point...saving the chalk dust to figure out a snap line at some point...