Retro is a summer event outfit available from the Risian Vendor for 750. It is tradable and thus can also be found on the exchange. The outfits are modelled on those worn by the "thralls" and the captured Enterprise crew in the Star Trek: The Original Series episode The Gamesters of Triskelion.
The costume has male and female variants of the top, two sets of bottoms for each and unique boots, gloves and neck accessories duplicating the look from the episode. The male and female versions are boxed and traded separately.