M23 Pro Circular Metric Connectors Phoenix Contact M23 Pro Circular Metric Connectors offer uniform solutions for signal and power transmission. M23 Pro connectors also feature the Phoenix Contact ONECLICK fast-locking system that connects devices quickly and safely. The ONECLICK system has an optically, haptically, and acoustically clear locking position for protection in harsh environments. Phoenix Contact M23 Pro connectors offer a rated voltage of up to 300V signal or 600V power. The series also provides vibration resistance up to 20g.