vacuum tube :the absorbing rate of vacuum tube up to 0.98. Absorbing rate D58*1800mm exceeds 20% than D47*1500mm type vacuum tubeStructure All-glass ... heat loss coefficient0.3~0.5W/(.)Resistant Hail25mmLife aged15 yearsCommon Vacuum tube Size:47mmx1500mm,47mmx1800mm,58mmx1500mm,58mmx1800mm,Primary advantage: 1) CE, ISO9001 ...