All HP cylinders come with a 10 year hydrotest date stamped. All HP cylinders are within 2 years of stamped date. Meets DOT and/or ISO regulations. DOT number is stamped on the tank. Rated Safety on Valve: 3,360 psi. Manfacturers Cylinder Specifications: 20 cu/ft Steel High Pressure Gas Cylinders: Working Pressure = 3AA2015, Test Pressure = 3360, Diameter = 5-1/4", Length = 13-7/8", Weight = 9 lbs. It is advised to contact your local gas supplier(s) to verify their policy on re-filling customer-owned cylinders. No Return on Full or Empty cylinders due to DOT regulations associated with the transport of the cylinders. In cases where damage occurs during transit, Weldfabulous will do our best to correct the issue. Please contact us for any questions or concerns. Shipping only available to Continental US (Lower 48 States).Understanding date stamps: The "hydrotest date" is the number stamped before the " + * " markings. The "service pressure" is the number stamped before the "SPUN" marking.