TrolMaster Hydro X Sensors Sensor:4 in 1 Sensor for Hydro X Pro and Hydro X Plus (MBS Pro) you can rely on Bluelab’s you can rely on Bluelab’s pH Probe to give you accurate and fast measurements every single time pests and more with excellent clarity the MBS PRO can be placed in multiple locations throughout the growing area to provide spot measurements from multiple sensors (Up to 50 sensors can be connected to the Hydro X Pro) The sensors can then be used together (averaged) or separately in order to control a specific section of the grow area by assigning a sensor to a specific control device The optional CO2 Sensor (MBS S8) measures the CO2 PPM within the growing area