I don't know if this quite fits but one of the most useful items that I carry and some times multiples of, are bandanas. They can be used to shade your neck, your ears, wetted tie around your head or your neck for a cooling effect, as a wash cloth, dish rag, dish towel, pot grabber by folding it wrapping it around the pot and twisting the bitter ends together, a hot pad, a filter to remove sediment from water, a tourniquet, a sling, put a rock in it and toss the bear bagging rope over a tree limb, wipe sweet from the brow, use it to remove dew from your tent fly, blow your nose in it (off course after you've filtered your water). truly one of the most versatile piece of equipment you could carry. The uses of a bandana could probably a thread of its own.

flp