This automatic controller for liquid nitrogen is a unique supply tank switching system that maintains liquid control. The controller provides the automatic operation of dual tank switching. A LED gauge reflects the readings of the external temperature probe and monitors the tank condition continuously. The solid state audible alarm system has a visual indicator and a "push button" to allow you to mute it under close supervision. The tank switcher is activated by any automatic level filling system. Slave units may be added in quantities of two or more to expand the storage capacity for your specific needs. The 2020 system includes a 1/4" solenoid manifold, and 1 system slave. The 2020 system and all Gordinier products carry a conditional one year guarantee on materials and workmanship.