The elastic allows the item to fit comfortably and the cord can be used to fix it tighter. The cord is also stretchy so it expands with the body compared to a non-stretchy cord that would cut into the body.
Round Elastic Cord 1mm/1.5mm/2mm/2.5mm, Stretch Elastic Bead Cord for Crafts
PROFESSIONAL BONADEX WAISTBAND GARMENT ELASTIC WITH OR WITHOUT DRAWSTRING CORD
40 METER TO 200 YARD Elastic Black White Full Roll Braided elastic flat Cord
Twill Elastic Band 2.8" 2 Yard 1 Roll Flat Elastic Ribbon Cord Navy Blue
Everlasto 'Lastoflex' Elastic Bungee Cord Shock Cord Rope Black 10mm
4/6MM Black/White Elastic Flat Cord Sewing Braid scrunchies
