Yes, but you must follow the directions on our website to ensure the shipment is properly prepared. Simple attach the “eco M/T” adapter to the empty bottle by screwing it into cylinder threads, which ensures the bottle is completely empty. Click on the “EcoSmart Returns” button on our website and complete the form for a Free Return label. Next place the empty cylinders in a box (with the “eco M\\T” still attached to each bottle) and attach shipping label. No Hazmat paperwork is necessary since the “eco M/T” guarantees there is no pressure in the bottle.