The A. Schild 1339 is a mechanical watch movement that features the Breguet hairspring and combined settings for the escapement wheel and third wheel. The differences between the 2609A, 2609A.1, and 2609B are not known. There exist some detail differences within the family that cannot be attributed to specific variants, such as long or short regulator hand, 1 or 2 crown-wheel screws, 8 or 16 balance screws, with or without recesses for casing screws, and Incabloc or Poljot shock devices. This movement offers manual winding, a sweep second function, and was commonly used around 1965.