Ordering Description Product number Description: NT-20 Nitrogen, 20 cu ft, Cylinder, CGA-580 Product number: 0916-0145 Description: NT-55 Nitrogen, 55 cu ft, Cylinder, CGA-580 Product number: 0916-0326 Description: NT-40 Nitrogen, 40 cu ft, Cylinder, CGA-580 Product number: 0916-0028