1988-P Jefferson nickel struck on a 1988-P Roosevelt dime, and with strong design detail showing from the underlying dime. Also, the coin has a reeded edge, which is from the dime. Double-denomination nickels struck on dimes are rare, and one of the scarcer double-denomination types, although they occasionally come on the market for sale (just not often.)
This is a very beautiful example, with super detail showing, and also in a fantastic grade, being as high a grade as we've ever had. A number of the existing examples are lower mint state grades, such as MS-62-MS-64, and this is one of the best looking examples in existence, since it is MS-67 and has very lustrous, problem-free surfaces.