Bees wax - Natural.
This is a lighter colored bees wax that has been filtered down to 30 microns.
There are several uses but the two most common uses are to wax thread for sewing sheaths and the second is to soak sheaths in a mix of Neatsfoot oil and bees wax to make the sheath.
tip: In a double boiler (you can burn and ruin bees wax if it gets too hot) melt bees wax. Bees wax melts at 147F degrees. Add an equal amount of Neatsfoot oil. Keeping the temperature at 150 or less (use a candy thermometer), drop your completed sheath into the hot mix to soak. It will only take a minute or two. Pull it out and let it dry on newspaper. Just before the excess wax turns solid, wipe off the excess wax/oil mixture. If you try to soak a sheath in this mixture much about 150F, you will end up with a fried sheath that looks like a fried pork rind.
tip: Use bees wax to give your sheath stitching thread a quick coat before use. The wax will do a couple things, it will slow the fraying of the thread as you hand stitch and it will help lock the thread in place since it tends to be a bit sticky.
tip: Bees wax is a great rust preventative and is non-toxic.