Automatic Transmission Cooler Lines

PTFE hose (or TFE) is a teflon inner core hose as compared to regular braided line which has a nitrile core. TFE isn't affected the way nitrile is when in contact with certain fuels or fluids. I'm sure you have all seen the add on trans coolers with the spongy hoses attached to them, or those ever pesky rubber fuel lines that are swollen and sweating gas. It doesn't happen with PTFE hose. This is actually the same type of braided line that "Steel Braided" brake lines are made of.