Aha! A large, easily replaceable striking surface. Better yet, keep some spare circles *inside* the jar to replace them. The jar would hold far more matches than one circle could last for anyway.
Going on a camping trip is such an exciting adventure. Getting back to nature can be very refreshing and spending time in the great outdoors, away from the hustle and bustle of everyday life can be very rewarding. What makes it more fun is that there are things you can do to bring a bit of convenience in your camping zone.