Portable gravity lift

Were you looking for the more permanent Grav Lift?

The Portable Gravity Lift is a piece of Covenant deployable field equipment. It is only available in Halo 3.

Operation
Once deployed, the Portable Gravity Lift unfolds and projects a bluish-purple gravity beam that propels the player into the air - exactly the same as the Covenant's larger version, the unmodified Gravity Lift, but on a smaller scale. When placed near a wall, a player can use this device to jump over it. Doorways can also be blocked with it, by sticking enemy players on the ceiling, or if in Forge place it horizontally so it pushes the player away. It has the power to lift vehicles, such as the Mongoose, and other objects besides players into the air. Fragmentation grenades tossed at the lift will fly off in directions which can be manipulated by the player to damage enemies.

One tactic that has been used was deploying a gravity lift and then sending a power drain or grenade up to the enemy above.

It is activated like all equipment in Halo 3 by the X button

Forge
When in Forge you can place an active gravity lift that doesn't require pickup for activation. So in-game it will already be active.

In Forge you can place a gravity lift on top of a weapon holder. If done correctly the gravitational force from the holder will turn the gravity lift sideways. So instead of lifting you up vertical it will push you horizontal. This can be used to keep people from entering doorways or certain areas.

Disadvantages
Usage of the Gravity Lift inside (with a roof above) can trap the player, as they cannot move out while pressed against the ceiling. However, this can also be used as a defense. Also, portable or not, the Gravity Lift can still be destroyed by conventional weaponry and will self-destruct after ±30 seconds. An active Gravity Lift will not survive a fall from a great height.

Appearances
The Portable Gravity Lift was seen in the H3 ViDoc while a group of players were attacking High Ground. To the untrained eye one would suppose that a player just grenade jumped, but there was a pad on the floor that was radiating a blue light similar to the Man Cannon. It is another piece of equipment similar to the Bubble Shield, Power Drainer, Trip Mine, and Radar Jammer.

The Portable Gravity Lift was confirmed on Bungie.net.

Trivia

 * The Gravity Lift is used in obtaining the Cowbell Skull, on "The Ark" level of Halo 3.