18 1/2”’ | Hand Wind | Swiss Lever | Small Seconds |

Remarks:

• Movement family:
  • Ultra 41: Monometallic screw balance with Breguet hairspring, no shock protection
  • Ultra 410: Monometallic screw balance with flat hairspring, Incabloc shock protection
  • Ultra 420: Monometallic screw balance with flat hairspring, Antichoc 102 shock protection, different balance cock compared to calibers 41, 410
  • Ultra 421:  Minimal changes on the dial side compared to caliber 420: polished setting lever spring, Drilled hole around the escape wheel jewel, presumably for attaching a cap jewel

• Listing ID: 2807
• Manufacturer / Brand: Ultra
• Caliber: 420
• Size in French Lignes: 18 1/2'''
• Size range mm largest diameter: > 40 mm
• Shape: Round
• Winding: Manual (Crown)
• Hands Setting: Crown
• Seconds Hand: Small seconds
• Escapement: Lever (Swiss, English, Glashütte)
• Date, Day, Month...: None
• Jewels: 15
• Setting Lever Screw/Pin Position: Right
• Balance Position: Right (0 - 120°)
• Shock Protection: Antichoc 102
• Beats per hour: 18,000
• Balance Type: Monometallic screw balance with flat hairspring
• Power Reserve: Unknown
• Production Period: Unknown, probably from around the end of the 1950s
• Identification: Marked U 420 under the balance.
• External Link: https://watch-movements.eu/blog/en/2018/07/01/ultra-watches-and-movements-from-france/
• Country: France
• Contributor ©: Uhrforum.de member Badener (Andreas Kelz)