Janome Adjustable Zipper Foot Screw On This foot can be set to sew on each side of the zipper. The edge of the foot guides the zip to ensure straight placement. Can also be used as piping foot for thicker piping including the heavy jumbo cord. Its a screw-on type foot, and can be adjusted to fit snugly against the cord when covering your own piping or when attaching commercial piping.
The standard zipper foot that came with my Janome machine was no good for chunky piping and the piping foot only takes piping up to 5mm - so this was the alternative and it works a treat. There's a danger now that everything I make will be piped!