TaraBraid 1312' w/ 9 stainless steel conductors, blue & white
Tarabraid, is a braided twine, unlike most polywire which is only twisted. Braid is stronger than twine and also provides a more reliable conductor. When the conductors in twine are damaged you generally lose that conductor for the length of your entire fence! In braid, conductors are intertwined and contact each other multiple times per inch which means in most cases that if your wire is damaged it will reconnect and re-energizes less than an inch away from the damage point!
So what is the difference between having 9 stainless strands vs the mixed-metals 3SS + 6 tin-copper strands? Electric current resistance. To put it plainly, the mixed-metals polybraid has about 10x less resistance than the 9 stainless. That means you are able to carry your energizer's pulse much further. You may then ask, why even make the 9 stainless? Well, stainless wire has greater tensile strength, costs less and for runs less than a quarter of a mile, the drop in voltage is not much to worry about.