Kershaw (the knife company) sales the Fire Steel’s with their name on one side and Fire Steel’s name on the other side. I got mine at Smokey Mountain Knife Works but it should also be available at their web site www.eknifeworks.com for about $9.
I did not like the new stamped striker that they come with and now use a piece of Saws All blade. I also looped it up with 550 cord as I did not trust that little plastic piece to hold up long. I also wrapped the top of the striker with grip tape to keep it from rattling so much.