SL1 Probe Expansion Module by Digital Aquatics (30-0015-000) Multiple Inputs 5 input ports provide a broad range of monitoring options. 1 x pH We currently sell PinPoint brand pH probes. Although any standard pH probe with a BNC interface should work with the SL1. 1 x ORP We currently sell PinPoint brand ORP probes. Although any standard ORP probe with a BNC interface should work with the SL1. 1 x Temperature port Digital Aquatics Temperature Probe 2 x Switch Ports For use with DA part number 30-0017-000, this gives customers the ability monitor switching devices and take action on that input. No compromise Design Small, compact design and convenient mounting tabs make installing the SL1 a breeze. Upgradeability The SL1 also has upgradeable firmware so you can take advantage of our developing feature set; and firmware updates are always free!