The one-piece is size M, with a slightly elasticated waist that's slim-fitting, and appears to be a pullover style. It has a neckline, so it seems like it could be worn early in the spring. No lining. The navy blazer is thin, and wearing it as a set would be suitable for formal occasions♪ Of course, they can be worn separately too♪ They're versatile. Although it's new, this item has some damage, such as stains, scratches, or fraying, so please consider it as a used item. I'm offering it at a low price. Please understand this before purchasing.