The ring adapter easily screws onto the front of any lens, and converts the thread size of your lens to the thread size of any other accessory (such as filters, hoods, flashes and lens converters). Extremely solid and lightweight. Specifically designed for your camera for a tight and secure fit. No wobbling or cross-threading. Your camera's lens thread size will be marked somewhere on the lens barrel. This number is always preceded by a "Ø" (diameter) symbol. For example: Ø37 = 37mm lens thread size. This number can also often be found printed on the back side of your lens cap.
The first number is always the lens thread size, the second number is the filter size of the accessory. If the first number is bigger, it's a step-down ring. If the first number is smaller, it's a step-up. A must have accessory to unlock the full potential of your camera!