The ETA 2638 watch movement, which was used from 1978 to 1998, and again from 2001 onwards, features a micrometer regulator. This movement encompasses several functions, including an automatic chronograph with 60-second, 60-minute, and 12-hour displays, regulated by a pillar wheel mechanism with center-minute and -second hands. It also includes a sub-second hand, a quickset day and date feature, a 24-hour display, and a hack feature.