Well my man. This is probably the wrong thread to try learn more about Oakleys in general I suppose. I try and pick up little tips and such as time goes by. You guys have been at this for years. And that's why I too have relied on your judgement. I 'do' listen to what you guys say. That letter thing by the hinge is just something small I picked up somewhere. i don't even remember where I heard that. And I did see that in some of my pairs. Didn't examine them all though. I suppose I don't want to bother you with a subject that might take up too much of you time if it isn't a standard with all Oakleys.