Heddles come in a variety of sizes called dents to allow you to control of number of ends per inch in your project. The standard heddle with each Kromski loom is 8-dent. Also available are 5, 8, 10 and 12-dent heddles. As you expand your weaving interests, you may want to have more than one heddle size.
Additionally, you may want to try using 2 heddles of the same blockdent size as the same time. This will allow you to approximate a 4-harness loom. The process is not as easy as a true 4-harness loom, but for the occasional need, this is a nice option. If you are interested in doing this, order an extra set of heddle blocks to support the extra heddle.