Professional 3/16 in Letter and Number Stamp Set, 36 pcsMfr #: CP23100 316LN Make precise and refined imprints on leather, wood, copper, brass, aluminum and mild steel Premium Chrome Vanadium steel with differential heat treatment to achieve optimal performance and durability. 62 HRC hard stamping end produces high quality imprints and keeps the edges sharp. 42 HRC tough hammering end excels at absorbing repeated hammer strikes and maintaining durability Large, true to size, and precisely machined 3 16 in.