* Surface of this kind of tube is smooth and the tube is colorless.

* The properties of the tube are: high purity (SiO₂>99.99%), abrasion resistance (any acid except HF acid ). Fire resistance (softening point 1700 centigrade). Low coefficient of thermal expansion (5.5x10-7/centigrade, heat the tube to around 1100 centigrade, then put it into ordinary temperature water, the tube won't crack, ).

* The surface can be done with gold plating.

* Gently using sizes:

1) Single outer diameter x double outer diameter: 8 x 17 mm, 11 x 23 mm, 15 x 33 mm

2) Length: 400 - 4000 mm