The Smiths Sectronic Mk II movement is basically similar in operation to the Sectronic Mk I. The construction of the balance and coil assembly is slightly different in that the coils are in the same plane as the balance and not at right-angles. There are two separate coil assemblies each with a concentric trigger coil and impulse coil (the two trigger coils are in series with each other as are the impulse coils) and therefore there are two trigger signals and two impulses in each direction of the balance's swing. There are still three hair springs to pass current to and from the coils so there is no real saving in complexity of construction over the Mk I. The hands are driven by a rack lever escapement working in reverse.