A mowing machine having a four-wheel drive mechanism, together with a mowing unit below the machine body. In a preferred embodiment, a separately manufactured contact plate can be mounted to a movable magnet in order to be actuated to \u201con\u201d and \u201coff\u201d state of the capacitive switch. If not, a custom display property is then evaluated. The invention concerns the field of timepiece movements. The acoustic stack is primarily used in pulse-echo analysis of metal casing wall thickness and cement bond quality detection of wells. Here, a multiplicity of substrates are concurrently held by 2 to N\u22121 number of substrate holding devices among the N number of substrate holding devices and one substrate is loaded into the substrate processing chamber.