HEV Suit

The contrast in appearance of the HEV suit in Half-Life and Half-Life 2.

The HEV suit or, mods formally, the MARK IV/V Hazardous Environment Suit is worn by Gordon Freeman throughout the Half-Life series to date. Gordon first puts it on in the locker room before entering the Test Chamber in Black Mesa during the starting chapters of Half-Life. He wears it throughout Half-Life even after the defeat of the Nihilanth at the end, whereby the G-Man allows Gordon to keep it. Upon his appearance in City 17 at the start of Half-Life 2, he is in civilian clothing, but again acquires the HEV suit upon reaching Dr. Kleiner's Lab in the chapter, 'A Red Letter Day'.

The suit itself acts as very powerful body amour, able to protect Freeman from the various hazards he faces. However, for the suit to protect its user effectively, it requires energy to supply its battery power, effectively producing almost an invisible shield around the user, able to absorb damage of all kinds; at full power, the suit is even able to repel a missile from that of an RPG. The user recharges the suite's energy supplies by using various power points found around Black Mesa in Half-Life and around the power points found in or nearby Combine checkpoints or outposts in Half-Life 2 and Episode 1. It is because of this suit that Gordon is able to live so long in all the danger that he faces.

When used in Half-Life, the suit is known as the MARK IV version, giving the user a HUD (so the user can keep an eye on their health, the suit protection levels, weapon inventory and the direction of the enemy if hit), a powerful flashlight, and a morphine administrator if wounded. Upon its reappearance in Half-Life 2, it is known as the MARK V version, including the HUD, the flashlight and morphine administrator, as well as new additions, such as a sprint function, a zoom function and a modified anti-toxin administrator, to combat any toxins within the user if detected.

Trivia

• The power distribution between the two versions differs. In Half-Life, the flashlight had its own power source, but in the version used in Half-Life 2, the flashlight, along with the sprint function and the water-to-oxygen converter used underwater, are all linked with the main power supply of the suit. For example, if you were underwater with your flashlight on in Half-Life 2, your power source will rapidly diminish.
• On full power, the flashlight on the MARK IV version lasts longer than the flashlight on the MARK V version.
• The fact that the G-Man took the HEV suit off Gordon Freeman at the end of Half-Life, only for it to be waiting for him again in the arms of Dr. Isaac Kleiner gives the good indication that the G-Man was contacted by The Resistance when asked for help by some of its members for Gordon Freeman's help in their dire situation. This is most likely the Vortigaunts' doing, but it could anyone within The Resistance who already knew of the G-Man's grasp on Gordon.
• In Half-life, If the user touches biohazards, even without submerging, its shields wear down drastically, dropping several units at a time until the icon vanishes.