Klasse' Twin Stretch Needle Size 75/4.0mm 1 German-Engineered Steel Machine Needle This needle type ideal for embroidering and is excellent for heirloom sewing and decorative topstitching. The size indicates the distance between the spacing of the needles. Since needles are fixed on a nylon block, use it at slower speeds and not for prolonged periods of time. Unique curved design at the clearance-above-the-eye "CAE" stress point distributes pressure equally which makes Klasse needles much stronger then other flat conventional needles