This replacement buttonholer knob (part # 163721-656) is specifically designed for Singer 600 Series Touch & Sew sewing machines. This control knob allows you to select and adjust buttonhole settings on your vintage Singer slant-needle machine.

Specifications:

• Part Number: 163721-656
• Type: Replacement (aftermarket)
• Designed for Singer 600 Series Touch & Sew
• Function: Buttonhole selection and adjustment

Machine Compatibility:

This part is specifically designed for the Singer 600 Series (Touch & Sew) and fits a wide range of models within that class:

620 Series: 620, 625, 626, 628, 629

630 Series: 630, 630E, 635, 635E, 636, 638, 639

640 Series: 640E, 645, 646, 648, 648E, 649