Count on it to work, wet or dry, even with damp kindling. It's so dependable, it's been adopted by the U.S. Armed forces for their survival kits. And all you need to make it work is a knife.
By scraping the "shaving edges" with the blade, you will accumulate a pile of magnesium shavings. Then simply scrape the "sparking insert" to ignite the shavings to temperatures of 5400°F., hot enough to light even the most stubborn campfire! It's size makes it convenient for pocket or tackle box.