The Powerbase refers to the Sega Master System. The 3D glasses use a dongle that plugs into the card slot in the front of the unit, rather than into the cartridge slot on top. Compatible games include Zaxxon 3D and Missile Defense. They work with the Power Base Convertor plugged into a Genesis/Megadrive as well.
-KKC, who has two of these, which does him a fat lot of good being blind in a eye.