Rated to use on all soft metals and stainless steel (if you are a newbie, "rated" means it's specifically rated yes/good/go for it).
Knives are hardened steel and none of our stamps should be used on knife blades.
Just because a stamp "can" stamp in stainless, doesn't mean it will be easy. We do not recommend this metal for beginners. Stainless steel is very difficult to stamp on because it is such a hard metal. The larger and/or more intricate the design, the harder it will be to impress into stainless. Tape your blank to your bench block and consider using a 2 lb hammer.
We highly recommend buying a few stainless steel blanks to use as practice pieces.