Provides Automatic Switching From Main Tank To Auxiliary Tank Rear Panel Has Hose Barbs For Gas Connection 9x5x7" Mounts On Top Of Any Standard Co2 Incubator Alarm Sounds When Tank Pressure Drops Below 5 Psi Do Not Exceed 50psi. Operating Instructions: Tun On The Power Switch Located On The Back Of The Unit. The Light By The Tank Currently In Use (Tank 1 Or Tank 2) Will Come On. When The Tank Pressure Drops Below 5 Psi The Alarm Will Sound Momentarily While The Unit Switches To The Other Tank. If The Second Tank Is Also At A Pressure Less Than 5 Psi The Alarm Will Continue To Sound Until The Tank Switch Is Turned Off Or Pressure Is Restored. The Tanks May Also Be Switched Manually By Depressing The Button Labeled Tank Switch. During This Switching Procedure The Alarm Will Sound Until The Button Is No Longer Depressed. Tubing Information: Clear Polyurethane Tubing 5/16" OD X 3/16" Id