This is a product called whipping twine and it is used to wrap the ends of rope to keep them from becoming unraveled. The whipping twine is unique because it is waxed and comes in some real nice standout colors. The wax on the twine provides two big benefits. First, it allows the twine to pass through the rope nice and smooth, and secondly, the wax on the twine allows the final whipped assembly to sort of "weld" together and hold tight when you are done.
6 color choices - Red - Blue - Green - Gold - Black - White
If you are going to be whipping arborist ropes (like the 16 or 24 strand rope) then this is the whipping twine to use.