What are some things to look for when buying a ferro rod? And does anyone have a suggestion for one? Also, are magnesium and flint strikers like the one above above different from ferro rods? I have the former, and I noticed it seems to be scraping material from whatever metal I use to strike it. Ferro rods on the other hand, in all the videos I've seen, seem to be what get's scraped to produce sparks. Thanks!