The winding direction of the thread bobbin is indicated in the bobbin case - the arrows on the cover show the rotation direction of the motor. Installation Steps: 1. Remove the battery from the device. 2. Open the bobbin case by simultaneously pressing the two release buttons. 3. Take off the cover of the bobbin case and remove the bobbin. 4. Push the thread ends of the new spool out of the slots in the trimmer spool. 5. Insert the new bobbin into the bobbin case so that the arrows indicating the direction of travel are visible after insertion. 6. Thread the two ends through the opposite eyelets. 7. Replace the cover on the bobbin case. 8. Pull on the ends of the thread and repeatedly press the locking button until the two ends protrude. Colour: Black Size: Diameter 1.6mm Package Contents: 4pcs compatible with a well-known brand spool Warm prompt: 1. As different measuring methods may vary, a deviation of 1-3 cm may occur; please ensure this is acceptable before ordering. 2. Due to different monitors and lighting, the picture may not reflect the actual color of the item; we appreciate your understanding. 3. Only the package contents listed above are included, excluding other products.