The NanoSPARK Flint Kit includes 5 replacement flints and 2 replacement O-rings. Fresh flints help maintain optimal performance of the NanoSPARK. As the flint wears down, performance gradually decreases. Replacing the flint is simple: unscrew the tinder capsule and remove the QuickLIGHT tinder. Then unscrew the small brass screw carefully, as it is spring loaded. Remove the spring and tap out the remaining flint. Insert one new flint into the hole, place the spring back in, slide the brass screw onto the spring, and screw it back together. If the old flint is stuck and sufficiently worn, you may insert a new flint behind it. If the old flint is too long, the spring may bind when reassembling; in this case, remove the new flint and continue using the old flint until it wears down enough for a replacement to fit. Extra flints can be stored in the NanoSPARK tinder capsule beneath the QuickLIGHT tinder. Approximately 5 extra flints will fit. The ferrocerium flint functions even when wet. Provides up to 500 strikes for fire starting.