So how are you to figure out which ones work? I have spent a while playing with many
the ones with the powdered chalk I had issues with loss of chalk and having to play with it to get the correct amount coming down, owning several so that I can do both dark and light fabrics, Pencils I had to have a separate sharpener so that I can get a good point and the triangular one, would get broken and then I had to try to use a bit I could find...so I began to see what was out there here is my choice!
Chalk Pencil Cartridge Set, now by Clover
I Love this pen, it's width allows you to see the chalk and with all of the colors it gives you the ability to work on dark and light fabrics, You do need to have patience so that you do not skip your line, it is easy to break these and the carrier for the extra is flimsy, do take the time to tape one side so that it opens and shuts, or you will drop the extra chalk out!
Again now packaged by Clover,
This one I did not like....the pencil is very fine and comes in White, Pink, and Green. I found the pencil lead would break easily while trying to make a line, and so this was very frustrating. I also have to say the thin line was hard to find on dark fabrics.