The Tremor Pak is a third-party version of the Nintendo 64's official Rumble Pak, a device designed to vibrate the N64 controller during selected games to enhance realism. For example, the Tremor Pak might cause the controller to vibrate when a gun is fired or when the player takes damage.
The Tremor Pak uses AA batteries, causing it to be heavier than the Rumble Pak, which uses AAA batteries.[1] Unlike the Rumble Pak, the Tremor Pak has two levels of vibration.[1]
Variant versions were released with a built-in Controller Pak (a memory storage system); some models used the N64 console itself as a power source, eliminating the need for batteries (though the vibrations were weakened as a side effect). An additional variant was the Tremor Pak Plus, which featured a slot for a Controller Pak with a switch to select between the controller pack and vibrate.