Eterna cal 1438 U

Eterna caliber 1438U
based on ETA cal 2433 (Eterna was the co-founder of ETA)
Automatic winding, 18,000 vph, power reserve 44 hours
Function: hour, minute, second, date
Diameter: 27.60 mm
Thickness: 4.85 mm
Balance spring: flat hairspring