Tube, 5 mm, highest quality, ASTM type 1, class A, borosilicate glass. Each and every precision 5 mm NMR tube is 100 % gauged to meet the most exacting standards and ideal for sealing directly to vacuum manifolds, joints and valves. Supplied with a cap and features a sandblasted marking spot. Tube, 5 mm, highest quality, ASTM type 1, class A, borosilicate glass. Each and every precision 5 mm NMR tube is 100 % gauged to meet the most exacting standards and ideal for sealing directly to vacuum manifolds, joints and valves. Supplied with a cap and features a sandblasted marking spot.