Capillary tubes are either 100 mm or 90 mm in length and have an inside diameter of approximately 1.3 to 1.4 mm. You can select from tubes that are open on both ends or closed on one end. Borosilicate rimless culture tubes unique made for culture test. Tube is available in a variety of sizes. Culture tubes are made from Borosilicate glass tubing, with fire-polished top rims and uniform wall thickness for maximum heat transfer and chemical resistance.