I have a friend that sends me quilts in those "whatever will fit" boxes from the UPO. He always includes everything -- quilt top, batting, backing and thread. I don't send the thread back -- usually use about 1/2 of the cone. It's HARDER fitting the quilt back in the box than when it comes to me. When he sends them, they fit nicely and the box doesn't bulge. When I send it back in an old or new box, the box bulges. I've wondered the same thing.................