... efficiency 2, easyly installation 3. energy-saves high efficiency vacuum tube Solar water heater Specification:1) Vacuum tubes: Φ47 x 1, ... 500mm, Φ58 x 1,800mm, Φ70 x 2,100mm2) Vacuum tube size: 15, 16, 18, 20, 24, 26, 28, 30, 363 ... system fitting for families and work units5) The effect of temperature preservation can last 72 hoursPacking:Standard export carton and foam