Stays from the first part of the 19th century often had a wide, vertical center slot in which a long, straight busk made out of wood, ivory or whalebone (often highly decorated with cavings or poems) which could be inserted into the center slot for support. Busks were not always worn and could be removed easily according to your activity. Generally busks were worn for formal or evening functions and taken out for leisure. http://www.antiquecorsetgallery.com/article.php?article=28
This wooden new busk you can order at http://www.mantua-maker.com/catalog.html
A busk (also spelled busque) is the rigid element of a corset placed at the centre front.
In stays, the corsets worn between the fifteenth and eighteenth centuries, the busk was intended to keep the front of the corset straight and upright. It was made of wood, ivory, or bone slipped into a pocket and tied in place with a lace called the busk point. These busks were often carved and decorated, or inscribed with messages, and were popular gifts from men to their sweethearts.
In the middle of the nineteenth century, a new form of busk appeared. It was made of two long pieces of steel, one with loops and the other with posts, that functioned in the same way as hook and eye fastenings on a garment . This made corsets considerably easier to put on and take off, as the laces did not have to be loosened as much as when the corset had to go over the wearer's head and shoulders. The second half of the nineteenth century also saw the invention of the spoon busk.http://en.wikipedia.org/wiki/Buska baleen busk from 1780 http://www.antiquedress.com/
a wooden busk from the early 19th century http://www.antiquedress.com/