Round/Flat White Elastic / Black Elastic Cord 1mm-75mm Sewing Elastic Face Mask. Cord Width: 3mm, 5mm, 6mm, 7mm, 9mm. Colorful 5mm Flat Elastic Cord for Sewing Face Masks Art Crafts Stretch Bands. White & Black Flat Quality Elastic Cord Stretch Band For Masks Clothing 5/6/7mm.