This is the optional thermal probe for the CellShield. When used with the CelShield it will prevent pack damage due to overheating. When using the thermal probe, if the battery temperature rises above 150 degrees, CellShield will reduce the throttle command sent to the ESC in an attempt to bring the battery temperature back down. If the battery stays above 150 degrees, CellShield will enter soft cutoff mode. When using the thermal probe, CellShield alerts the user to temperature faults by flashing the red Temp light. The thermal probes are extremely thin, and can often be inserted between the innermost cells of the pack, where pack temperature is highest. Dimension Engineering