The Model 661 is a small economical unit with temperature and low level alarms for liquid nitrogen (LN2) dewars. It is a self contained unit featuring large LED readout, Temperature Alarm Setting, Low Level Indicator, Work/Mute button, Remote Relay and an Audible Horn. The unit comes with a bracket that easily attaches to the handle of any size dewar. Secure the Model 661 onto the bracket at a position for viewing of the Temperature and LED Level indicators. 117 volt AC (220 volt AC Option)