These needles are suitable for Industrial Overlock Sewing Machines, with Model DCx1 and a size of #18. Size 11 is suitable for thin fabric, size 16 for slightly thicker clothes, and size 18 for thick clothes, jeans, etc. Choose the appropriate sewing machine needle based on the material type and thickness. The length is about 37mm/1.46". The package includes 10pcs of 100% brand new Industrial Lockstitch Sewing Machines Needles.