A closure sew-in install is a popular and versatile hair extension technique that provides a natural, seamless look. This method involves sewing in hair wefts along with a lace or silk closure, which is a small, hairpiece designed to mimic the natural scalp. The closure is typically placed at the crown of the head, end of eyebrow to end of eyebrow covering the area where the extensions are installed, creating a flawless and realistic hairline.