We are all familiar with the standard Swedish firesteels (like Light My fire). The KSF Custom Firesteels take firesteels to the next level.
Instead of simply sending a shower of sparks like other firesteels, these throw balls of molten metal. These take a little bit of practice to use, but once you master it, you will never go back to a regular firesteel.
Simply take the sharp spine of a knife, hacksaw blade, or the like and scrape the steel quickly like you are flicking the sparks off the end. You will have to experiment to get the right angle and speed to get the best results.
These will fit into the Bark River Knives Bushcraft Sheath firesteel loops as well as all of the KSF Leather firesteel loops. They are 3/8" in diameter.