Diameter: Approximately 3.6cm. This is a Seiko Skyliner Calendar hand-wound men's watch. It was occasionally used from my father's watch collection. There may be some stains and minor scratches on the edge of the dial, as well as some scratches on the crystal, due to use and storage, but the glass surface is relatively clean and in good condition for its age. Please examine the images carefully (there is a reflection of fluorescent light). The strap has been replaced with a non-original mesh stainless steel strap (apparently, this is the strap it came with when it was purchased used). This strap is free-size, so you can adjust it to the perfect length each time you wear it. It's a hand-wound watch from about 50 years ago, so I cannot guarantee its future operation, but it was running without any major errors at the time of inspection (observed for about half a day). There were no instances of it stopping immediately after winding the hand-winding stem (crown). The quick-change date function switched by moving the hour hand back and forth between the 3 o'clock and 9 o'clock positions after setting the time. ***OH history is unknown... Also, I have not performed any OH maintenance myself. If you are concerned, please have it repaired and maintained yourself. There are no accessories. I am very sorry, but please do not purchase this item if you are not familiar with used items, are overly sensitive, do not understand the above explanation, are anxious, or have never handled antique items (especially mechanical ones). Mercari is a platform for private sales. This is a used item in its current condition and has been inspected by an amateur (there is no such thing as 100% perfection), so please understand. #Seiko #SEIKO #SeikoSchoolTime #SEIKOSCHOOLTIME #SCHOOLTIME #SeikoHandWoundWatch #HandWoundWatch #MechanicalWatch #SeikoTomony #Tomony #SeikoMechanical #CITIZEN #Citizen #CitizenMechanical #CitizenHandWoundWatch #SeikoChampionCalendar #SeikoChampion #SEIKOchampion #SeikoSkylinerCalendar #SeikoSkyliner #SEIKOSKYLINERcalendar #SEIKOSKYLINER Movement: Hand-wound