The Konami Hyperblaster ("Justifier" in the US) was a lightgun produced for the Playstation, SNES, and Sega Genesis. The Playstation version is green or dark blue in colour, while the other platforms are blue and pink. The pink version cannot be used in a single player game -- instead, it plugs into a blue gun in order to play two-player games from a single controller port. The Playstation version is compatible with some PS2 games, but only works in controller port 1 of the PS2 (i.e., does not support multiplayer on that platform).
Source: Wikipedia, "Konami Justifier", available under the CC-BY-SA License.