This attachment allows you to wind smaller spools of thread, such as industrial serger thread, using your sewing machine's bobbin winder. It is compatible with empty thread spools up to 6 cm tall, such as those from Schappe Spun (#60, both 200m and 700m sizes). 【User Reviews (Personal Opinions)】 ☆ It saved me in an emergency when I ran out of serger thread for just one color! ☆ Winding the thread is super fun! ☆ I use it to share thread with students in my craft class. ☆ It requires some technique, like using a pen to wind the thread evenly, but it's convenient because you can wind serger thread onto spools longer than a bobbin. ☆ It's convenient and fun to wind, I even uploaded a video to social media! 【Important Notes】 ○ When attaching to a home sewing machine, align the spring on the bobbin winder shaft with the indentation in the hole (located on the back of the marking on the base of this product) until it clicks. ○ To reduce wobble, you can wrap masking tape around the shaft or insert a small piece of rubber band between the shaft and the hole. ○ It is made to fit snugly to prevent wobble (we have confirmed it works with several sewing machines, but if it's too tight, carefully widen the hole with sandpaper wrapped around a chopstick). ○ A recess has been added to the bottom so it can be used with some industrial sewing machines like JUKI Spur. ○ Secure the thread spool by tightening the nut to balance it. ○ Do not overtighten the nut, as it may break. ○ Use it safely at a sufficiently low speed (less than 60 RPM). ○ High-speed rotation may cause it to break and fly off. ○ Materials: Base = Polylactic Acid (PLA), Screw = Iron, Decorative Nut = PLA ○ Usable lifespan: Approximately 30-50 uses ○ Use a pen or similar to move the thread up and down to wind it evenly on the spool. ○ It may not work with older sewing machines that use thin plastic bobbins. ○ Use the bobbin winder properly or use a "sub-tension" device to apply the correct tension to prevent loose winding. ○ Weight: Approximately 20g ○ Condition: There may be fuzz and printing marks characteristic of 3D printing. ○ Simple packaging using recycled materials such as empty candy boxes. ○ Thread, thread spools, bobbins, sewing machine, instruction manual, sandpaper, and receipts are not included.