Neptune Systems manufactures their own temperature probes in-house. Why? Because they saw the level of early failures due to using off-the-shelf temperature probes like those used in stand-alone digital thermometers as well as those used by other aquarium controllers. These probes often fail because they were never designed to be permanently submersed in saltwater. We custom build our temperature probes using a proprietary method that encapsulates the business end of the probe itself from the corrosive effects of long term saltwater submersion.