Sets refers to any type of articles of clothing or group of things which are considered to be of the same kind and that can be paired together and are so used. Layettes are one example of a group or set of articles of clothing.
About Tie Bars:
Tie bars are menswear accessories designed to decoratively hold a necktie straight on the front of a shirt. Tie bars generally have the shape of a narrow metal strip and sometimes feature a centered icon or a sports team logo.