I think you mean RWS EPNS-A1...
RWS is just the manufacturer.
EPNS stands for "Electro Plated Nickel Silver". Nickel Silver (sometimes stainless steel) is the base metal onto which silver is plated. Despite its name, nickel silver contains no silver at all, but is an alloy of nickel, zinc & copper. A layer of pure silver is deposited electrolytically on the base metal to give a silver finish.
A1 is just the thickness of the silver plating. It usually varies between 30 - 35 Microns. It's one of the Highest Grades of Silver plating.