This is a diopter correction lens for Leica cameras. The diopter is -1.0. Compatible with all M-series cameras. A screw adapter is required when using it with the Leica M10 series. It's also suitable for those with nearsightedness who use a Leica with contacts or glasses, and just need a little more clarity. The lens is in beautiful condition with no scratches. Thank you. *Please note that price reductions will be made at my discretion, and I will not accept individual offers.*