Heat collecting surface: 2.6sqmVacuum tube specifications and quantity: Ø47 x 1,500mm, 25pcsWater inlet and outlet size: 1/2", 3/4" or 1"automatically replenishing water ,no need to manuanlly feed water ,using anti-freezeand anti-bilge media ,with better endurance to climate using the heat tube as the collector ,it has good anti-freeze performance and willnot cause system collapse due to damage of one tube producing area:China