Hang tag string usually are connected with hang tags. So, the size must be considered, especially the string end diameter.
The hang tags will leave a hole or metal eyelet for the string to penetrate. The string end diameter must be smaller than the hole diameter or eyelet diameter.
The hangtag string length is also important, if hang tag is large, the string needs to be longer; if hang tag is small, the string needs to be short and thin.