Some details:
Line Collection : Oversized pilot
Watch name : Observer Winder
Dial : black
Reference : 8558-6OB-a1
Case Material : stainless steel (316L)
Glass :mineral
Surface : matt
Water resist ; 3 ATM
Glass back : yes
Size : 47.5 mm
Crown : not screwed
Band : leather
Strap width : 22 mm
Movement : Manufacturer Fabrique d'Ebauches Unitas, Tramelan, Switzerland (since 1898) now ETA SA
Calibre :nUnitas 6498
Date : no
Weekday : no
System : hand winding (manual)
Energy : mechanical
Jewels : 17
Vibrations : 18'000/21'600 A/h