Review on HORUSDY 36-Piece 6mm Number & Capital Letter Metal Stamp Set (A-Z & 0-9) Ideal for Imprinting on Metal, Plastic, Wood, Leather - 1/4 (6mm) by Linda Diaz

Stamped a bunch of keys so I can't mix them up. Hitting takes a hard hit. I landed a few less moderate hits on the first few hits and sometimes left multiple stamp marks - not easy to keep it in place after each hit. That's how I found out that a powerful punch is enough. Remember that strong is a relative term. I'm not trying to put a stamp through the key just to make a clear impression. Very well made, every letter or number of the stamp is clear and precise. Judging by the recoil on hammer blows, the dies are well heat treated and hard. I was a quality inspector in a past life and can see harshness without even doing an RC test on a car.