The collar stay or collar stiffness is a plastic accessory or other rigid material that is inserted into the end of the collar to give it stiffness and prevent could be fold. The shape is rounded at one end and pointed at the other. It is inserted into a piece placed on the lower collar. The size and shape of the collar stay must be adapted to the shape of the collar. The collar stay ensures that the collar rests on the clavicle, remain rigid and in correct position.