Currently working and was tested over a 21 hour period and kept near perfect time, may have lost 10 seconds. It may need a service to keep absolute perfect time. The 10k gold filled case is 51mm in diameter. 1945 Hamilton, Grade 992B, Model 5, 21J, 16S, lever set, stem wind, railroad grade, 6 adjusts, double sunken dial with date serial number C127955. Nice dial, just needs a light clean, perspex has a lot of wear and needs replacing.