Omega 300 (R 17.8), Main spring, no: 770

• Manufacturer: Prima, no: 130 J 29

• Fits cal: R17.8, 300, 301, 302, 310, 311

• H: 1,30
• D: 8,5
• F: 0,09
• L: 290

Versions:

• R17,8: sub second, rhodium plated bridges, to 1949.
• R17,8AM: sub second, antimagnetic, rhodium plated bridges, to 1949.
• R17,8SCAM: center second, antimagnetic, rhodium plated bridges, to 1949.
• 300: same as 17,8, sub second, rose gold plated bridges, from 1949.
• 301: same as 17,8AM, rose gold plating, from 1949.
• 302: sub second, incabloc.
• 310: same as 17,8SC, from 1949.
• 311: same as 17,8SCAM, from 1949.