I received the Orvis "6 lb" IGFA mirage fluorocarbon tippet today, and it is labeled .006" in diameter. It also says that it is 2.3 kg (5.06 lb) in breaking strength. This means that it is the same size as the Orvis 5x mirage fluorocarbon, and has the same breaking strength. I am tempted to conclude that it is identical to the 5x, but just labeled differently.

Regardless, it should be essentially the same as the 5x, and at the sale price ($4.00 for 40 meters), it is a pretty good buy. I will substitute it for the 5x and save a few bucks.