One thing to keep in mind when securing items like knives, flashlights, etc. If you will be in a situation where the tethered item may become entangled, such around swift water, while rappelling, etc., make sure whatever string/twine/line/cordage will have a relatively low breaking point. Several deaths each year of individuals who tied their knife, flashlight with 550 cord or accessory cordage, had the item become entangled in rocks, tree limbs, etc. and drown or become seriously injured, because the item would not break away. Personally for situations where this might occur, I buy cheap (4/$1.00) plastic key ring coils, which have a low breaking point, but still allow me to tether important items I do not want to lose. Pete