Curtain ring: the outer diameter is approx. 37 mm/1.45 inch, the inner diameter is 30 mm/1.18 inch. For curtain rods less than 27 mm/1.1 inch, please ensure the size when purchasing. Quantity: 40 black metal curtain rings in the package, enough for daily use and replacement. Installation: Slide the curtain ring onto the curtain rod one by one, and the curtain hooks into the small ring. Then you can easily slide the curtain. Good Design: The curtain rings are well polished with a burr-free surface. Made of durable black metal, these curtain rings are sure to be effective on your curtains. Wide Application: These curtain rings are widely used for most types of curtains, such as shower curtains, window curtains, French window curtains, etc. Please check the size before purchasing. Set of 40 metal curtain and rod hanging rings, 30mm inner diameter Sturdy curtain ring: Made entirely of robust metal with a strict design, the ring rolls smoothly and won't deform or fall off suddenly. Durable