This is a 16S Illinois W. C. Co, “Rival”, a very high quality case. THE PICS MAKE THIS CASE LOOK LIKE IT HAS SIGNIFICANT BRASSING. THIS CASE HAS NO BRASSING, THE PICS JUST AREN’T MY BEST. The only drawback is that it is personalized. This case was made for a pendant or lever set movements. There are a couple imperfections from use over the years so please use the photos to make a good decision. Case: Open Face, both covers screw on/off. Maker: Illinois Watch Case Co. Material: 20 year gold filled. Outside D : 51.0 mm. Inside D : 42.5 mm. Please use the photos as a big part of the description and please contact me with any questions.