Switch is a modification for Quake made by Peter Porai-Koshits. This modification allows the player to turn on and off the Quad Damage as needed, allowing them to conserve it for a more needed firefight. To turn the "switch" on and off, the players just need to press impulse 133.
Players with the Quad Damage deactivated will still fire shots that sound like they have the Quad Damage. Furthermore, they will be lit up, meaning players cannot camp when having a Quad Damage. The main method of telling if the "switch" is on or off is the visual blue effect, which is only shown when the Quad Damage is in use.