UNIVERSAL SIZING - Each ring has an inner diameter of 32mm, with an outer diameter of 39mm. Perfect for 30mm curtain rods or smaller, and looks great on brass, copper, chrome, and more! SMOOTH GLIDING - Has a flawless finish that provides an extremely smooth, back & forth gliding motion. Easy to move, & causes less noise than normal rings due to our extra smooth finish. STRONG & STURDY - Made from heavy-duty steel, each piece is carefully coated with a durable, rust-resistant, black coating, resulting in a very strong, rust resistant, ring with a flawless finish. KIND TO CURTAINS - Great for either the lightest or heaviest of curtains or drapes, and will not damage, stain, rip, tug, or deform them in any way. Easy to attach & remove without any issue. 3 YEAR GUARANTEE - Designed in Britain. We are so confident in our product that if you are not completely satisfied within 3 years, then contact us, & we will provide a full refund immediately.