Expand the real-time control, monitoring, and predictive maintenance of your Arduino Opta with the Arduino Pro Opta Digital Expansions. Power up your Opta Digital Expansion and multiply your system's capabilities with 16 programmable inputs for connecting your digital sensors and 8 additional relays for controlling your machines. Arduino Pro Opta Ext D1608E: 16 programmable voltage inputs, 8 electromechanical relays 250 V/AC, 6A.