glass tubing

The standard length for glass tubing is a nominal 4 feet.

Flint glass tubing

Outer Diameter (millimeters)	Wall (millimeters)
4	0.75
5	1.05
6	1.05
7	1.10
8	1.10

Pyrex® tubing

Tubing is now denominated exclusively in metric sizes, although a few odd sizes represent pre-existing inch sizes, such as 51 mm and 178 mm (2 and 7 inches). Outer diameters from 2 millimeters up to 220 mm are available, from 2 to 20 mm in 1-millimeter increments. The standard wall thickness is 1 mm ± 0.1 mm for outer diameters from 6 to 12 mm, and 1.2 mm ± 0.1 from 13 to 20mm, but several wall thickness.

Capillary tubing has a very narrow bore, as little as 0.5 mm in tubing with an outer diameter of 5.5 mm.

See www.corning.com/lifesciences/