List of UNSC crates
Scattered throughout multiplayer and campaign levels on Halo 2, Halo 3, Halo 3: ODST and Halo: Reach are UNSC crates, or large boxes, that contain supplies for ground based Marine forces. The contents of crates can be identified by their labels, and range from portable generators to armored boots. Although their only actual use in the game is cover from enemy fire, they do reveal a bit about the UNSC military, and play a key role in the environment of maps and campaign levels. They can also serve as cover or platform.
 Halo 2
There is a range of different types of crates. This section contains information on all of them, ranging from smallest to largest. Kits are small crates that appear to be carried by Marine ground forces. Barrels contain liquid supplies. Small crates carry equipment used by ground troops, and large crates contain large pieces of equipment for use at fixed positions.
The first crate can be found only once or twice in the game; it appears to be a small medical kit Marine medics would use to treat the wounded. It has the word "Rescue" along with the international medical symbol. It is likely able to be found in various campaign levels at Marine positions, but it can only be found once in multiplayer on the map Foundation.
 Nerve Gas
This container containing VX 7 nerve gas can be found in a Jiralhanae encampment inside the armory. It is placed under another crate so it is pretty difficult to find. There's another one on Metropolis on top of the building where Sergeant Banks and a turret are next to a medical crate. The crate has been spotted on the multiplayer map Foundation as well. Perhaps it is with a bit of dry humor that Bungie placed this small crate right next to a medical kit within the same room.
Type: VX 7
 Blitz Can
This crate or barrel is for emergencies. You can also find blitz cans with Hydrogen fuel.
Item: Water - Pure
This barrel can be found all over on multiplayer maps and Marine encampments in campaign. It appears to be a barrel of water for hygiene, cleansing, drinking, etc.
It is likely this is used by Marine ground forces to fuel various equipment, including generators and Warthogs.
 Small Crates
 Gas Mask
S90 Gas Masks are used by ground forces for protection against chemical or biological weapons.
Serial Number: 7880-53-413-1990
Item: Gas Mask/KR3/INF/BLK
Weight: 112 LBS
CH252 Helmet, the standard Marine armor helmet in Halo 2.
Serial Number: 9325-80-548-4127
Weight: 82.6 LBS
 Body Armor
The M52B Body Armor is for use by Marine ground forces for protection from energy and ballistic projectiles.
Serial Number: 2580-55-270-4193
Item: Body Armor/C-M/INF/W-OD
Weight: 173 LBS
 Armored Boot
The VZG7 Armored Boots are the standard issue boots for UNSC Marines.
Serial Number: 5893-22-418-2524
Item: Armored Boot/INF/V-OD
Quantity: 10 Pairs
Weight: 81 LBS
 M6D Pistol
Item: Pistol/M6D 12.7MM Rec. Op.
 Large Crates
 Machine Gun
Type/Item: M247 7.62 Gas Op. Auto Linkless
Weight: 893 LBS
 Emergency Food Prep Station
The MK71 emergency food preparation station is used by UNSC Marines to cook food in field conditions.
Item: Emrgncy Food Prep. Station
 Replacement Transfer Case
A transfer case is a part of the four wheel drive system found in the Warthog. The transfer case is connected to the transmission and also to the front and rear axles by means of driveshafts. The transfer case receives power from the transmission and sends it to both the front and rear axles.
Item: Rplcmnt Transfer Case/M12LRV IDPG FT-DR
Weight: 203 LBS
 Security System
Weight: 305 LBS
 Portable Generator
This portable electric generator/hydrogen fuel cell is likely used at fixed positions for power.
Item: Port EL Gen/HY F Cell 18 KV
Weight: 273 LBS
 Resupply pod
 Halo 3
Halo 3 features most of the same crates as seen in Halo 2. Interestingly, the crates in Halo 3 have the exact same labels as in Halo 2, even though the pieces of equipment they represent have been changed.
 Halo: Reach
There are several types of UNSC crates in Halo: Reach. The redesigned basic crates no longer bear labels describing their contents and are emblazoned with the UNSC emblem instead. Below the lid, there is a net presumably intended to keep the contents in place. However, all crates encountered in the game are empty. Additionally, the game features black ONI crates and heavy Misriah Armory weapon crates.