Stamps sets are great for stamping gold, sterling silver, gold bullion, and soft metals. Made with black coated carbon hardened steel. Each set includes letters A-Z, numbers 0-8 along with the ampersand symbol (&) stored in a durable box. The "6" stamp can be flipped over to also be used to mark a "9". Character height: 1/16" / approximately 1.5 mm. Not recommended for use with stainless steel.