I know I've said this before, so I apologize for the repetition, but...

An army P38 can opener makes an excellent striker for these ferrocerium-rod firestarters. It's really not noticably larger or heavier than the steel strikers that come with these things- smaller and lighter than some.

Plus, it opens cans. Easily. That's a pretty big plus when you need it.

I'm pretty much never without a BSA Hotspark when out of the house, but I wouldn't consider carrying a single-purpose striker with it.

The P38 in my keycase has even made it through the airport screening a couple of times. I have a whole box full, so I don't care much if they confiscate one or two.

Avoid the imported imitations, though.