The Peter Pan collar and some other flat collars are designed to be detachable. A detachable collar is a shirt collar separated from the shirt fastened to it by the studs. The collar is made of different fabrics from the shirt. Usually, the collar is white. The stiff collar is attached at the back of the shirt before the shirt is donned. The detachable collars allow for more experiments. They may be tied or buttoned onto the neckline for added effect. You often see these in the form of faux fur on winter jackets.