Description
Based on your photos, this appears to be a vintage Seiko 5 Automatic watch from the late 1970s to early 1980s. Without the case-back reference number, some details are approximate.
Features
Brand: Seiko
Series: Seiko 5
Movement: Automatic (self-winding mechanical)
Country of Origin: Japan
Era: Late 1970s–1980s
Case Material: Stainless Steel
Crystal: Mineral Crystal
Case Shape: TV/Cushion-shaped case
Dial Color: Silver/Champagne with black chapter ring
Display: Analog
Calendar: Day & Date display at 3 o'clock
Bracelet: Stainless Steel bracelet
Crown Position: 4 o'clock (typical Seiko 5 design)
Jewels: Usually 17 or 21 jewels (depends on the movement)
Power Reserve: Approximately 40 hours
Water Resistance: Originally may have had basic splash resistance, but after 40–50 years it should NOT be considered waterproof. Have the seals replaced and pressure-tested before exposing it to water.