Explain the types of button hole that sewing machines can stitch

Keyhole Buttonholes

This keyhole buttonhole has a bar tack at one end and a round opening at the other edge.

The keyhole accommodates the shank of the button nicely without pulling on the buttonhole. It is a strong buttonhole suitable for suit jackets and coats in medium to heavy-weight fabrics.

The opening for the keyhole can be cut after the buttonhole has been stitched by using a small eyelet punch.