Bill Nelson (editor) The measurements of the name and the "OA" are the only features listed in the Blue Book v6 that distinguish this patch from the S-5. I have never encountered a patch with the S-3 measurements, so I'm skeptical that those measurements are correct and/or a good way to tell S-3 from S-5. I have seen two reverse-side varieties of S-5, and I'm wondering if one of them is actually S-3. 25 days ago