Selector switch head Ø22 2-position spring return Ronis 3131A. range of product: Harmony XB4 – device short name: ZB4 – mounting diameter: 22 mm – head type: standard – return: right to left – type of operator: spring return – operator position information: 2 positions 90° – type of keylock: Ronis 3131A – key withdrawal position: left.