I recently replaced my aging flint/magnesium blocks. After carrying them and using them for many years they were in bad shape. I looked on ebay and found the flint rods, about 1/4 thick by about 4 inches long. Five for about $15.00. I also found someone selling magnesium shavings, a gallon ziplock full for about $10.00.
I now carry my flint rod and two match cases tied together. One match case has cotton balls/pj and the other has the shavings.
I have found that they light easy and a small pile of the shavings not only burns with a flame for several minutes but it leaves a red hot ember for about five minutes. The 4000 degree flame will light almost anything even if it is cold and wet outside.
I always carry a lighter, stick matches and lifeboat matches as well. Although the flint is my backup I find myself lighting my fires with it just for the practice.