Jeff:
I just took a look and realized that what is referred to as "Bridle wire" is just a misnomer nowadays. Today's similar wire is actually known as "E Block wire". It looks the same, but bridle wire is one-pair, 14 gauge solid copper. The stuff that's being used today is 20 gauge, copper-coated steel. Each conductor has a black outer jacket. A second internal jacket is color-coded green, red, black and yellow. When you strip it, you can see what color the wire is by looking at the end. I guess it's just another one of those RJ45 things.
Here's a link to Superior-Essex's site to better describe it:
https://www.superioressex.com/products/premises/e-block.htm
