KNX bus system: yes; KNX radio bus system: no; Radio bus system: no; LON bus system: no; Powernet bus system: no; Bidirectional radio: no; With bus coupling: yes; Removable bus module: no; Control LEDs: no; With LED display: yes; Number of inputs: 4; Input voltage: 3.3 V; Input voltage type: DC; External query voltage required: no; Minimum device box depth: 40 mm; Installation material: switch mat/building control KNX - Hager binary input 4-way KNX TYBS704A Secure UP.