... structure Glass material High borosilicate 3.3 glass External pipe diam eter and thickness Φ=47±0.7mm &=1 ... &=1.6mm, Φ=70±0.7mm &=2.0mm Internal pipe diameter and thickness Φ=37±0.7mm &=1.6mm, ... ±0.7mm &=1.6mm, Φ=58±0.7mm &=1.6mm Pipe length 800mm, 1200mm, 1500mm, 1600mm, 1800mm, 1900mm, 2000mm, ... tube Working Principle:Tri-target solar vacuum tube, connecting with water tank or manifold, when it works, ...