ZB4-BK1543Overview of Schneider ZB4 BK1543 Selector Switch Head The Schneider ZB4 BK1543 is a head for illuminated selector switches from the Harmony XB4 ZB4 series. It features a chromium metal construction with a red handle, designed for 22mm panel cutouts. This selector switch head supports 3 positions with universal LED illumination for clear operator indication. Key Features of Schneider ZB4 BK1543 Illuminated Selector Head: Provides visual feedback via