... the coating from bursting, aging, discoloring, function attenuating because of long time burn under the sun, prolonging its life span ... is activated promptly once sun irradiate. The upper surface of semi-cylinder of tube heated by sunshine directly, and the under ... to 15 years) Standard PYREX high borosilicate glass with coefficient of linear expansion 3.3×10-6/°C, complies with international ISO1776 ...