For those of you who, either at my recommendation or independently, purchased the “Dritz Chalk Cartridge Set” chalk holder, or (perhaps more so for you who) did not purchase the Dritz model because it is made of plastic, it should be noted that the chalks that come with the Dritz holder are 3.8mm in diameter, and can be inserted into the “Koh-I-Noor 3.8mm Clutch Pencil 5356″ which is made of metal.
I have never seen the Koh-I-Noor 5356 in any store, but it is available from several online retailers. I won’t attempt to bias you for or against any particular retailer. The down side are that the 5356 does not come with a supply of chalk or a sharpener.
I have yet to compare the Koh-I-Noor colored artist’s leads to the Dritz chalk sticks in terms of marking and washability. So far, the Dritz chalks have lasted several years and one pack may be a lifetime supply.