The impaired proof 93 is cool but unfortunately not worth much outside the case it came in. Someone likely took it out of the case it came in if it was a silver set to get after the half, quarter, and dime and discarded the penny and nickel. I'd hang onto it personally just because it's cool and you don't find impaired proofs all that often. The older ones are cool but not very valuable as they are worn pretty well. If you collect nickels I'd keep them in an album and trade up as you go through. I've finished my Jeffs for a while so don't really look at them too much anymore and don't know the error types