A removable collar can be attached to any outfit, be it a plain white t-shirt or a floral 60s-style dress. You've got collars with animal print, leather, a plain white Peter Pan collar kind or a more geometric, futuristic one. The more options you have ready before you, the more you get to play around with your outfits. Despite its heavy tilt towards androgyny, the detachable collar can flit between genders. Again, it depends on how girly or manly you make them when styling. :)
Detachable collar at Emporio Armani, SS12.