nathan wrote an answer about Oakley Flak Jacket XLJ Replacement Lenses on November 3, 2011
XL and XLJ lenses are absolutely interchangeable on ALL oakley frames. The lenses are the same except xlj's offer more coverage around the bottom and outside. I have half and flax jacket frames that I have both xl and xlj lenses for. Not interchangeable between models, but both frames take both xl and xlj lenses. There are no separate xlj frames.