Andoer 18pcs Filter Adapter Step Up / Down Ring Set 37-49-52-55-58-62-67-72-77-82 37-82mm 82-37mm Rings (SET) The ring adapter set includes 9pcs set-up rings and 9pcs set-down rings. If the first number is bigger, it's a step-down ring. If the first number is smaller, it's a step-up. The set-up ring converts the thread size of your lens to the thread size of any other accessory (such as filters, hoods, flashes and lens converters). The set-down ring converts the thread size of your accessories to the thread size of any other lens. Made of high quality anodized black aluminum (metal). Extremely solid and lightweight. Specifically designed for your camera for a tight and secure fit. A must have accessory to unlock the full potential of your camera!