Omega and Lemania jointly developed an automatic chronograph movement for introduction in 1972. Cal. 1040 would power the new Omega Speedmaster Mark III, a range of models with modern tonneau cases to succeed the Speedmaster Professional Mark II. The Mark III was produced with three different cases, eventually gaining the Speedmaster Professional moniker. It would also power the Speedmaster Professional Mark IV, introduced in 1974.
Cal. 1040 has an unusual arrangement of hands and subdials. It is a 2-register movement, with 4 central hands and subdials at 6 and 9 on the dial