18g, 16g or 14g Cannula Piercing Needles. The European method of piercing that uses a cannula needle then a standard piercing needle. The needles are made from surgical stainless steel and are encased in a plastic sheath. Once the skin has been pierced, you remove the needle and leave the sheath in the piercing. Insert the jewelry into the end of the sheath and then pull the sheath through the piercing with the jewelry.