Multi-film gas sampling bags are made of layered films that consist of polyethylene and aluminum films. It has a stronger ability to resist gas permeation than any other films. This kind of bag is widely used in petroleum chemical industry, environmental monitoring, scientific experiments for gas sample collection and preservation. Fitting type: Metal connecting type,Double metal connecting type, Model L Valve , Model L of Double Valves ,Straight Pole Valve,Straight pole of double Valves. Features: Non-permeable Opaque - to protect collected gases against ultraviolet light Do not chemically interact with gases Simple to maintain and do not require technical training to operate . *Note: 0.5-30 liter volume, we can supply other size according to customer requirement, too. Carton measure:57x47x30cm Carton gross weight: 15kg.