It is made out of paracord, which is a nylon rope. I use 550 Paracord, which means each strand can suppost 550 pounds. It comes in about 50 colors.
I can make any length needed from Miniature to Draft. Shorter would be cheaper, longer would be slightly more.
Also in an emergency situation the reins can be unbraided and and you can use the rope for other uses. There is approximately 96 feet of rope in each set of reins.
They are also easily washed in a bucket of water with horse shampoo or with dish soap.