These new, high quality large capacity aluminum bobbins fit industrial sewing machines using large capacity sewing hook. Aluminum bobbins are considered the top-end "Luxury Bobbins". They add much less resistance or drag to the bobbin thread tension, perfect difficult or problem applications. Aluminum is usually machined to higher tolerances than steel. They are recommended by Sewing Machine Manufacturers for Machines with thread undertrimmers. Suitable for many single needle straight machines, good for most industrial sewing machines. Package includes 100 pieces of large aluminum bobbins. Note: These bobbins are not slotted. They not fit in many quilting machines bobbin rewinders., Weight: 1.01853565044 pounds, Manufacturer: Tuidzljd