A 4×4 lace closure is a type of hair closure that uses four strands of hair to create a natural-looking scalp line. This type of closure is often used in conjunction with lace wigs or hair extensions to give the appearance of a full head of hair. The four strands of hair are sewn into place on a piece of lace, which is then attached to the wig or extension base. This creates a secure and realistic-looking scalp line that can be styled in any number of ways.