The Forster 451 watch movement, introduced in 1942, is the first calibre family to feature a bidirectional rotor winding. It offers optional regulators including Reed's and Incastar, the latter being the only large-scale produced regulator with a free oscillating hairspring. The Incastar regulator includes adjustable rollers that eliminate isochronism error caused by the gap between regulator pins. The movement also includes a range of functions such as automatic winding, sweep seconds, day and date-hand adjustment pushers, month adjustment pusher, and moon phase adjustment pusher. The Forster 451 movement has been in use since 1942.