This is a vintage Singer Adjustable Zigzag Attachment (Part No. 121706), a collectible accessory used to add zigzag stitching capabilities to vintage straight-stitch sewing machines.

The set shown includes the original green and white box, the metal zigzag attachment, and the specialized needle plate (feed cover plate) required for operation.

Key Details and CompatibilityCompatibility: Designed for use with "Singer Lock-Stitch Family Sewing Machines," including iconic models like the Singer Featherweight 221 and 222, as well as models 15, 66, 99, 185, 192 (Spartan), and 201.

Function: It converts a straight-stitch machine into a zigzag machine by moving the fabric back and forth under the needle. It features an adjustment knob to control the width of the zigzag stitch.Origin: These attachments were manufactured by Singer in the United States.

Does not include instructions