There are many types of equipments available in Halo 3. Some of the equipments are used for defense while others are for inflicting damages on the Covenant troops. The equipments are scattered throughout the missions.
The Bubble Shield when dropped will generate a dome-shaped force field around the player. It can protect anyone inside the Bubble Shield by preventing gunfire from penetrating the shield. However, anyone including the enemies can just walk through it. Grenades except the Spike grenades, just bounces off the shield. The shield will fade after about 30 seconds or when it suffers high amount of damage. The shield can be deactivated immediately by destroying the device. You can use the Bubble Shield when you suddenly find yourself under fierce gunfire.
The Portable Gravity Lift when activated will generate a force field, which will propel upwards, anyone who steps on it. It is great for reaching high perches or scaling walls. You can use the Gravity Lift to jump to a higher ground to escape from a pursuing Chieftain. You need it to jump up to a high platform to get the Cowbell Skull in The Ark mission.
Another useful equipment is the Cloaking device. With this device, you can be invisible for around twelve seconds. It is great when you are facing weapon-wielding enemies in a narrow walkway or trying to get out of a tight spot. It is best to move quickly away after activating the Cloaking device. You can still melee and toss grenades without being visible, but firing your weapons will affect your visibility.
The Invincibility device is another equipment to get out of tight situations. Once activated, you will be impervious for ten seconds, to all forms of attack including a strike from a Gravity Hammer. However, falling from a great height will still kill you.
