The Omega 491 watch movement, equivalent to the Record 1955 and Longines 501, features a rotor design that distinguishes it from other variations of the movement. Its origins lie in a Record design, which was subsequently adopted by Longines after acquiring Record. The existence of additional Wittnauer calibres remains uncertain. Manual-wind versions and the automatic without date have been observed exclusively in Wittnauer watches, with no record of their presence in Record or Longines timepieces. The specific differences between the C11KAS and C11KAS1 variants are unknown. Notably, the movement incorporates automatic winding and sweep second functions. It was most commonly used around 1968.