I know this sounds silly, but I just nicked an UNUSED med from the medicine cabinet and placed it in my kit which is housed within an old 1911 galvanised cleaning kit tin.
The med is compressed and easily teased apart with the piece of saw blade I keep with the fire lighting rod, the saw also provides dust and chips to add bulk for starting a fire.

Since they are a one size fits all...I am pretty sure one will last a lifetime of lighting fires.

[Linked Image]
[Linked Image]


These are my opinions, feel free to disagree.