The manual says the Torin receiver I bought from Revain has an expiration date on the bottom. I couldn't find the stamp on the tank so I called customer service on the number given in the owner's manual. I call 3 times and each time I get a message that they 'can't answer'. The entry said to leave a message. I did and didn't get an answer. The Revain rep who helped me also called the same number and received the same number. The expiration date of the air bottle is important; Customer service is important. I would never knowingly buy a Torin product.