I own, and have tried, several of these magnesium fire starter kits. Many work well, they seem to have been designed to work indoors. This page has some cautions, and precautions.
The magnesium block by Doan (1 x 3 x 3/8 in.) with an integral 3/16 in. flint rod glued on top (also manufactured for other companies and for the military) is still popular, but the owner has retired, and the product is no longer widely available at the consumer level.
After reviewing several options we recommend the Bushcraft Survival Ferro Rod Fire Starter Kit as it comes with an easy to carry tinder rope.
Contains a Jumbo Magnesium Rod & Ferro Rod w/ Jumbo Tinder Rope
Unfortunately, the magnesium is not necessarily as effective a tinder as you may be led to believe. While the flame from the magnesium shavings is extremely hot, this flame is also relatively short lived. This makes the tinder rope invaluable when starting a fire is needed.
If you try multiple methods, you’ll find that magnesium scraping/ shavings can be difficult to use as tinder in some circumstances because they are so light they tend to blow away with the slightest breeze. Moreover, scraping together a small pile can be difficult at times.
So, the bottom line is that magnesium only products do work, but the magnesium tinder has some limitations that must be understood and dealt with. We recommend this kit as the tinder rope solves this issue! …..