ImpressArts Sans Serif letter stamp set is a classic contemporary style typeface thats similar to Arial Its softer fuller look clean lines and rounded edges make it perfect for unisex projects Size 3mm Size is based off of the height of capital letters and the tallest lowercase letter Lowercase includes full lowercase alphabet and question mark stamps Rated for stamping on Alkem aluminum pewter copper brass silver gold other metals up to 56HRC Rockwell Hardness In order to prevent rust these stamp sets are lightly coated with oil Simply wipe down with a dry paper towel or rag before using Avoid wiping with anything wet water will cause stamps to rust Creative and unique metal stamp perfect for making jewelry DIY projects and customized presents or keepsakes Perfect for labeling your original crafts jewelry pieces