It is unlikely, but possible that available products may be out of stock. In this event you will be contacted to either cancel the order or go forth with an extended delivery date.
Patchwork foot # 57 with guide differs from Patchwork foot # 37 only in that it has a built-in seam guide along the right edge of the foot. It is therefore particularly suitable for patchwork projects with 1/4 (6mm) or 1/8 (3mm) seam allowances.