This is a customized part : double-needle walking foot + Tape Attaching Folder.

The gauge size (the distance from the center of the LEFT Needle to the center of the RIGHT Needle) is 5/16 inch, matching tape width is 35mm, the finish size ( after fold ) is 17mm.

This Folder folds the tape in on two sides downward with the edges meeting at the center. 

It will fit many double-needle walkin foot sewing machine like JUKI DU-122 HIGHLEAD GC20638....if you are not sure it will fit your sewing machine, please message or email us , we are happy to make sure it for you !