Digital Aquatics RKM SL-1 Module 1 x pH port: The pH port is a standard BNC connection. While any standard probe should work, we sugg 1 x ORP port: The ORP port is a standard BNC connection. While any standard probe should work, we su 1 x Temperature port: Digital Aquatics Temperature Prob 2 x Switch ports: Great for float switches and leak detectors. This port gives customers the ability LED Status IndicatorUL&gt;ConnectionsB&gt;&lt;U