The Light Phaser is a light gun controller created by Sega for the Sega Master System. It is the Master System's equivalent to Nintendo's Zapper for the Nintendo Entertainment System.
The Light Phaser is a plastic gun consisting of a light sensor (in the tip) which is focused on a small area of the screen; and a trigger (which corresponds to Control Pad button 1). When the trigger is pulled, a compatible game flashes the screen in a way that is detectable by the light sensor, and hardware built in to the console allows the game to determine where the gun is pointing. The phaser is heavier than its Nintendo counterpart, but considered by some to have a more responsive trigger and more accurate targeting.
As with all light guns, the Light Phaser was designed solely for CRT television sets, which were the standard for televisions during the 1980s and 1990s. The Light Phaser will struggle with LCD and plasma televisions and monitors, as well as projection screens.