... passed the artificial ageing test for 12,000 hours in the National Chemical Building Materials Testing Center ... to the solar irradiation and annual sunshine time, 10,000 hours’ testing is equal to 35 years’ ... solution of 40%NaOH or 40%H2SO4 for 24 hours, our products won’t change the shapes or ... set of accessories;Easy installation, saving labor and time;Accessory :main ridge tile ; diagonal ridge tile ...