The foot can be set to sew on each side of the zipper. The edge of the foot guides the zipper to ensure straight placement. The AcuFeed mechanism is great for zippers in thin or stretchy fabrics; it feeds all the layers through evenly for a polished look. 

Janome 

CM7P, CM17, Horizon Memory Craft 12000, Horizon Memory Craft 14000, Horizon Memory Craft 15000, Horizon Memory Craft 8900QCP, Horizon Memory Craft 9400QCP, Memory Craft 6700P, Memory Craft 8200QC, Memory Craft 8200QCP SE, Memory Craft 9450QCP, Skyline S6, Skyline S7, Skyline S9