Taking place the sheet a harder, sharp-edged steel, then fly to rub the top layer black sparks. There are no less than other fire starters. Very suitable as "Striker" for example, the back (!) Of small metal file on Swiss Army Knife or the SwissTool, etc. In my opinion, the supplied sheet is already obsolete. Finally, you will be outside but always at least have a knife there. Because of the fire starter itself well functioning wobbles, I give full marks, despite the defective sheet.
That sparks weaken a knife back in the structure significantly, as some say here, I think is a mistake. The sparks fly away quickly, and the small amount of heat, they leave there is discharged jiffy. Anyway, I have not experienced any significant warming even with five minutes Firemaking on my knife. It could be grabbed at the affected area still. Of the 600 degrees that would be the minimum required to make the steel again "soft", which is very far away. Since the mechanical stress on certain plays the bigger role.
Because the spark ultimately are nothing but burnt metal, and gunshot residue remain on the grater tool. This harms maybe the knife optics. Who therefore would rather carry a complete "lighter" on the ribbon, which was to replace the supplied sheet metal rubbing against a shortened to about five centimeters hacksaw blade. Simply break off an old saw blade in a vice appropriately. This has then also a nice hole in the end of the string (and can cut metal is thus in an emergency even). Then it is, with only a little practice and some tinder such as birch bark with spruce resin around it, the fire not do anything in the way.
If all of the domestic charcoal grill is much too complex, the doubt is right. For the fire starter is after all not made, and the handle for disposable Bic is easier. In a survival kit, the gas lighter is not reliable enough, because gas could flow out prematurely. Then and even when too wet conditions it is better guarantees as to the fire starter.
By the way: I am unclear why these things are always referred to as "magnesium rods". It is rather mischmetal. This is an alloy of the element cerium and iron - the same as in the "fire stones" of the gas and gasoline lighters.