This precision 5mm diameter, 7in long PYREX® Deluxe Plus NMR tube is made from quality borosilicate glass for compatibility with ground joints, valves, and vacuum racks. It is designed for use on NMR spectrometers running from 250 to 400MHz. The tube has an outer diameter of 4.97 + 0.000 to 0.013mm and an inner diameter of 4.20 + 0.013 to 0.000mm. This NMR tube can be used with the PYREX® Microcell system to avoid diluting valuable microsamples. This is the suggested replacement for Corning® item number 6981C-7. Not Graduated. Material: Borosilicate Glass Code 7740. Tube Style: NMR. For NMR: 250 to 400MHz. Camber TIR: 0in. Concentricity TIR: 0in. Inner Diameter: 4.2mm. Inner Diameter Range: + 0.013 To 0.000mm. Outer Diameter: 4.97mm. Outer Diameter Range: + 0.000 To 0.013mm. Length: 7in. Corning® #: 6980C-7.