Here is a summary of what the U.S. requires when offering guarantees (referred to as "warranties") on consumer products. (International readers, please investigate these in your own locality.) Please note, I am neither a lawyer nor expert on this topic, and I do not work for the FTC. I simply researched this for quite some time, and thought that you might benefit from my findings. Check with an authority — or the FTC itself — for any clauses below that you don’t understand.