FLINT STEEL FERRO ROD FIRE STARTER LIGHTER MAGNESIUM 6 8 10mm 3" 4" 5" 6" 8" 10"
Try at least middle sized rod like 6.5mm x 75mm or 8mm x 80mm or 10mm x 100mm - the thicker and longer the better as will be easier to use. Then you will find with practice and use you will get the best perforance from your rod.