The Oakley Full Metal Jacket (FMJ) is a highly coveted, expensive, and awesomely limited production watch.
It is also a color or coating on many different frames (ie. XX, Eye Jacket, Straight Jacket) which also several variation of colors (ie. FMJ +, 45mm, 5.56, 7.62, 9mm, Red, White, Copper, Gun Metal).
Oakley XX or Twenty is a frame that covered two Genereations with many colors.
First Gen - XX (O-Review)
Second Gen - New Twenty (O-Review)
The Oakley 5 3.0 is a completly different frame that is the third generation frame of the Five series which has technically 6 generations. The first 3 gens are very similar to each other and the last 3 gens are very similar to each other.
Fives - O-Review
Fives 2.0 - O-Review
Fives 3.0 - O-Review
Fives 4.0 - O-Review
Fives Squared - O-Review
New Fives Squared - O-Review