Material - These machine twin needles are made of high quality stainless steel and high quality plastic, sturdy and durable. Double needle design - Each double needle is equipped with 2 needles. You can easily thread 2 identical or different decorative threads while sewing in a straight line or pattern for a more beautiful look. Sizes - The double-stitch needles are available in three sizes: 2.0/90, 3.0/90, and 4.0/90. - 3.0/90 is suitable for decorating bright threads and thick fabric trims. - 4.0/90 is suitable for elasticated fabrics. Application - Universal sewing machine accessory, suitable for most sewing machines. Use scenarios - Decorative topstitching on garments or home decor by using two threads to create contrast or texture. - Attaching decorative trims or thick fabric trims along hems or edges for a richer finish. - Sewing elastic or stretch fabrics with the 4.0/90 size to maintain stretch and reduce fabric puckering.