Json Fluorocarbon Leader is highly abrasion resistance with a very low memory. It sinks faster than nylon and is almost invisible in the water, so it's a great choice for spooky fish. it turns over bulky flies easily and present smaller flies perfectly to wary fish.
Json Ultimate Leader is primary for streamers and nymphs with a heavier butt section and more power for turnovers with big flies. The leader has maximum strength and abrasion resistance. The leader has 30% maximum elasticity which helps when playing those big fishes.