M3 Pattern Personal Armor (Earth-5875)

The M3 Pattern Personal Armor is the standard-issue ballistic protective vest worn by the members of the UNSC Marine Corps and a key component to most UNSC Marine Corps BDUs. Designed and manufactured by Armat Battlefield Systems, it allows for the balance between lightness and comfort while also optmized for protection. It serves in conjunction with the M10 Pattern Ballistic Helmet.

Overview
The M3 Pattern Personal Armor consists of 14.5 lb (6.58 kg) of olive-green armor plating over combat fatigues. It is based on the French Armed Forces' cuirasse ("fighting armor"), and consists of a sandwich of materials molded to form a rigid shell. The outer layer is an ultra-light titanium-alumide alloy designed to provide structural strength and ablative protection against projectiles and lasers. Beneath this is a core consisting of a layer of boron carbide resin bonded to a layer of graphite-composite carbon fibre. Boron carbide is an incredibly hard ceramic designed to shatter a bullet on impact while simultaneously forming a conoid base to absorb its energy.

Beneath this, the carbon fibre layer provides ballistic protection at the point of penetration by delaminating across a large area, thereby absorbing more energy. Finally, on the inside of the armour is woven liner made of 1,500 denier Venlar fibres. This woven liner dissipates the remainder of the energy by deforming in the area of impact, and is also able to catch any spalling or fragmentation from the first three layers. Since any bullet or fragment impact on the armour shell tends to compromise its integrity and ability to provide ballistic protection, it is standard practice to discard damaged pieces and replace them with new sections immediately.

In practice, the stopping power of M3 armor is somewhat limited versus direct hits, particularly when dealing with high-velocity ball ammunition and High Explosive Armor Piercing small-arm rounds. However, it can be expected to stop low-powered ball ammunition and provide some protection against impact-fused explosive bullets and grenade or artillery fragments. Some stealth characteristics have also been included, such as curved and rounded surfaces to reduce radar signature, and infrared masking. While very resilient against ballistic weaponry, though it can easily be damaged by the Covenant's plasma weaponry. Temperature-regulation units are integrated to keep the wearer at optimum performance while limiting the need to change BDUs to suit the environment. The regulators also reduce the enemy's ability to track the wearer via thermal energy.

As standard, the M3 armor system is issued in a woodland camouflage scheme, but various patterns are available for operations in different terrains and climates. The surname of the individual Marine issued the armor is printed across the top of armor's chestplate. Additionally, many Marines elect to personalize their armor with slogans, pictograms and other personal touches. While officially against regulations, this practice is mostly tolerated, unless the troops are operating in high profile positions. The armor is fully adjustable and can be fitted over the top of the UNSC standard IRC Mk.35 Pressure suit for combat in low pressure environments.

Vest
The primary component of the M3 armor is a rigid vest, which protects the thoractic-abdominal region, front and back, between the upper abdomen and neck. This vest comprises a two-piece clamshell secured by plastic clips. At the top of the clamshell, above each shoulder, is a rigid load-bearing arch from which hang the webbing straps. These arches are padded underneath to protect the wearer's shoulders when the armor is loaded with additional weight. Two segmented pieces attached by webbing straps protect the front and side of the shoulders.

Inside the vest are remote biomonitors which monitor the wearer's life signs, including heart-rate, breathing and blood type; an optic cable connects these to the personal data transmitter contained within the M10 helmet. On the rear left shoulder is a bracket for attaching the TNR shoulder lamp. Also on the back of the armor are three mounting brackets for an individual pack (IP) frame. The IP is a standardized lightweight medium pack designed to carry up to 24 kg, attached to a carbon fiber 'A'-frame which clips directly into the rear mount. The pack is water repellent but not entirely waterproof, although additional waterproof liners are issued for each of the pack's main compartments and pockets. The mounting brackets on the vest can also accept the life support unit used in conjunction with the IRC Mk.35 Pressure suit, which is then connected directly to the thermal regulation suit and helmet.

Abdomen
Below the armored vest is a separate section which covers the front abdomen and groin. This is a flexible pad of rheological ballistic armor secured by a 'diaper' harness. A rigid armor plate is fixed to the lowest part of the pad to protect the genitals.

Headgear
All iterations of the M3 feature one of several versions of the standard-issue M10 Pattern Ballistic Helmet, which is painted to match the corresponding body armor. The helmet may be mounted with various accessories, such as a holographic tactical eyepiece, a helmet recorder, a boom microphone, polarized tactical goggles, a flashlight, or a night vision device. Marines sometimes wear balaclavas with their helmets, both in frigid and temperate climates. In hazardous situations, gas masks such as the S90 gas mask are worn.

Combat boots
Combat boots such as the VZG7 armored boots are worn with the uniform. They are sometimes equipped with different types of additional armor to provide greater protection to the lower leg.

Webbing
Velcro-lined heavy duty nylon webbing with side-release snap buckles. Comprises equipment belt with keepers, and suspender-style bandoleers that attach by snap straps to the load bearing shoulder pauldrons of the M3 armor's vest. Each bandoleer acts as grenade sling with four elastic loops for holding 30mm rifle grenades (18 total). A number of pouches can also be attached and these can be used for carrying items such as a bypass kit, personnel first aid kit, respirator, water hydration system or spare ammunition. A combat knife or pistol holster can also be attached to the webbing.