Blue Insertion Lace 4 inches wide plus selvage, by the yard, Vintage

Vintage insertion lace in a pale blue.  There are 4 usable inches plus the selvage for insertion.  No stretch

In my Oh-so-distant youth, this was often used it make long full skirts, using it between solid strips of fabric.  Also on crinolines (what's that?, right), slips & night gowns.

Insertion laces have no fancy finished edges, the edges are meant to be sandwiched between two other fabrics or with one & then top stitched out of sight.

Today you might use them to insert in jean legs, down the back of a blouse or in much costuming.