Metal curtain rings are typically used in conjunction with a metal rod to hang curtains. The rings are placed onto the rod and the curtain is then threaded onto the rings. This allows the curtain to be easily opened and closed by sliding the rings along the rod. The number of rings used is typically determined by the width of the curtain and the spacing desired between the rings. Metal curtain rings are durable, easy to use and are often used in commercial and industrial settings.