Currently working and was tested over a 22 hour period and lost approx 30 seconds. It will need a service to keep absolute perfect time. The stainless steel case is 50mm in diameter. 1957 Hamilton, Grade 992B, Model 5, 21J, 16S, lever set, stem wind, railroad grade, 6 adjusts, double sunken Montgomery dial, Railway Special with date serial number C444754. Dial has a lof of scratches & wear and may need replacing, case back has a dent.