The Bulova 2191 is an electronic watch movement that was used from 1972 to 1974. It features a special regulator that can be accessed by opening the battery cabinet. The stem can be released by sliding a mechanism. It incorporates a hack mechanism that stops the balance in a position that ensures reliable starting when the crown is pushed in. The movement offers a range of functions, including an electronically controlled balance motor, sweep seconds, quickset date through repeated crown pushing, shock protection, and a calendar feature.