No, it's not, but half of what people are wearing isn't "approved". As long as you look professional, you should be fine. Variations on uniform pieces like A Cut Above are so close, its hard to tell. The only place I'd say it's even a remote possibility of an issue is in Chicago. There's a particular person that gets his kicks off of looking for uniform infractions. There's also one or two grumpy old bastards that have anointed themselves as uniform Gestapo, but you'll likely never encounter them. There are very few pilots that wear ONLY M&H items.