This is a Elna # 125 double stitch cam that controls the stitching of the machine both side to side and front to back creating fabulous decorative and stretch stitches. This will fit on many of the older Elna sewing machines like the Supermatic, Super, and the SU. Please check your manual for compatibility. I have many more Elna Cams to post if you don't see the number cam your looking for please contact me. If you need any other vintage sewing parts feel free to contact with me, like mom always says it never hurts to ask. Thanks for shopping my store.