regular vacuum tube

structure: all-glass double-tube co-axial structureglass material: high borosilicate 3.3 glassexternal pipe diameter and thickness: Φ=47±0.7mm £=1.6mm Φ=58±0.7mm £=1.6mm                                                        Φ=70±0.7mm £=2.0mminternal pipe diameter and thickness: Φ=37±0.7mm £=1.6mm  Φ=47±0.7mm £=1.6mm                                                    
regular vacuum tube