"Microsoft Windows 98 Upgrade" for the PC, on CD-ROM, from Microsoft in 1998.  Includes the original genuine Windows CD-ROM.  The disc has scratches, but I have done a complete read test and it is entirely readable (no read errors).

The Product Key is on the sticker on the back of the slipcover.  This is the upgrade version so you need an older version of Windows to install it.

Buyer pays $4 S/H in the U.S.