This is a top high quality Left Edge Guide Topstitch Foot 

Fit for DURKOPP ADLER 69 267 269 Walking Foot Machine

The Outside Foot Has a Special Spring-Loaded Guide That Maintains A Perfect Topstitch On Leather Or Upholstery Fabrics.

The Guide Size is the distance between the center of the needle hole to the edge guide or the stitch line to the edge.