The A. Schild 1639 watch movement, introduced in 1956, shares similarities with the Eterna 1419U movement but differs with its operation at 1800A/h. Unlike the Eterna movement, it does not feature a ball bearing or a gold rotor. The A. Schild 1639 incorporates an indirectly driven minute mechanism, enabling the use of a large balance. This movement is characterized as automatic and has been widely utilized from 1956 onwards.