my local walmart caries the doan tool for about 6 bucks, it will do in a pinch. look in the sporting goods section.
that said you will find that the larger the rod is the bigger the sparks, so one of othe military fire steels that are sold by bagheera on this forum throw a whole lot of sparks. same as the blast match and the gerber strike force. so you can select the kind of rod that you need, bigger or smaller depending on what you need to do with it and how it needs to be carried. also you need to keep these dry when not in use, as they will disintegrate if they are chronically wet. like if you store them in a wet place, not if you get dunked in a stream-- they will light up just fine just dry them off. if you have used the rod, it is advisable that you coat it with some nail polish befor putting it away. some guys use bright orange polish so they dont lose the tool if it falls or is left at the fireside.