The Leica Sumitar's compatible filter size is 36.5mm, which is difficult to obtain. Furthermore, the threads are recessed, requiring specific compatible filters. This item is a step-up adapter ring that converts to the common 39mm screw-in size. By using this, 39mm diameter filters and lens hoods can be attached. This is a third-party ring equivalent to the Leitz genuine SOOQR. [Condition] This item was opened and mounted once after being purchased new. (Selling due to a different system build.)