A small piece of equipment, that still gets the job done, has the advantage that it will more likely be carried on your person, available if needed. It is small enough to keep with a set of keys or in your pocket, without being a bother. According to the manufacturer it will give in excess of 1000 strikes. Even if that's an optimistic number, the point is it will do the job. For strictly emergency use you can use a piece of shrink tubing to protect the rod , as I do for mine.
Many people prefer to carry a lighter and use that as their primary fire starter.
However, any lighter demands a reliable back-up since they can leak or run out of fuel. If you pack one in a kit, be sure to protect the gas release button so it will not be depressed accidentally in storage. Current production lighters sold in the U.S. have a child safety lock which serves well to keep it from being emptied accidentally. It's probably worth noting that the sparking device in these lighters can still be used as a fire starter, even if the lighter has run out of fuel. Of course, it isn't quite as easy to use them as such.