Singer slant shank ruffler #160629. From Singer 301A accessories box.
Notes from the UK:
For 301 slant shank sewing machine. Fits in place of the standard presser foot with operating lever engaging the needle clamp screw. Adjustable for 1, 6 or 12 stitch ruffling. Has an adjusting screw which regulates the fullness of the gather and an adjusting finger which sets the size of the plaits. For gathering the adjusting finger should be moved forwards towards the needle so that it is not in operation

Used but good condition, price includes shipping.