These quality Supply Guy design metal stamps will make a lasting impression on your jewelry and are manufactured to the highest standard for durability and alignment. Designs are made from heat-treated tool steel and are rated for use on stainless steel. Impression Size: 4mm, 6mm and 8mm Quantity Included: 3 Stamps Features: Rated for Use on Stainless Steel and Square Shank Design stamps can be tricky so for best results follow these simple steps: 1. Practice on cheaper metal before using higher end metals like Sterling Silver or Gold Filled. 2. Make sure there is no padding under your bench block. 3. Make sure you are working on a stable table. 4. Use a steel faced or brass hammer which weighs at least 1-2 pounds depending on the complexity and size of the design. 5. Hit the stamp more than once, but hold it steady making sure you don't shift at all between hits.