Methods of production and attachment to packaging are many and various and may also be subject to internationally recognised standards. In many countries, hazardous products such as poisons or flammable liquids must have a warning label. Metal labels, also known as anti-metal electronic tags, metal-attached tags, and anti-metal tags, are special tags packaged with a special anti-metal and electromagnetic interference material and electronic tags. Non-metal-resistant electronic tags cannot be read by electronic tag readers when they encounter metal. http://www.jfbutton.com/label/metal-label/