Not sure what they meant by "Twin Set", but mine came single without the under "dress"/lining...SO, unless you already have a strapless bandeau, knee length dress to go with this lace overlay, OR, are ok with wearing a lace dress without a lining, which I am not, This doesn't do you a lot of good! One bothersome thing about this is, I remember reading others that received this the same way.  Doesn't say good things when this happens repetitively.