Though the helmet will protect guards from taking damage from low caliber rounds, if the player use cheats and shoot the guard's helmet sufficiently, it is possible to kill the guard.

However if he is hostile to the player, his helmet will become bulletproof from player's 9mm bullet and shotgun buckshot weapons. However, in Source, the helmet will not protect from 9mm rounds or shotgun buckshot pellets if the guard is friendly to player.

The Helmet in GoldSrc versions of Half-Life will protect security guards from damage inflicted by bullets and the Crowbar.

In the playable Half-Life 2 Beta, the model of a Helmet can be found.

While removed in the main game, the helmet is still present in the multiplayer model.

The Opposing Force 'Otis' Security Guards were originally supposed to wear helmets, like their 'Barney' counterparts.

The Security Guard's Helmet in the Half-Life Alpha has the abbreviations 'MP' ( Military Police).

Note that this increment is based on numbers - For example, if the player use cheats to spawn multiple helmets or find more than one at a random spawn point while they have no armor, they can keep picking up the helmets until their armor is full. In Half-Life: Blue Shift, picking up the Helmet will gain 40 Armor points while picking up an Armor Vest will gain 60 Armor points. Instead, picking up a fresh vest or a fresh helmet is required to increase the armor points. Unlike the HEV Suit and Powered Combat Vest, the battery cannot be used for increasing the armor points. (In Insecurity, Chapter 2 of Blue Shift, Barney will have to get these for the guard at the counter to let him through, and in this case it's referred to as a Uniform) It is necessary to wear the vest in order to pass a secured area. The Security Vest, Helmet, and Glock 17 or Desert Eagle are important pieces of equipment for all security guards. These bullets penetrate through the Helmet, killing the guard instantly.

357 Magnum, Desert Eagle, or the Crossbow. The Helmet also cannot protect users from high-caliber rounds such as a.

The helmet does not protect the face, meaning a guard is still vulnerable to bullets. The Helmet protects a security guard from damage to the head, but only low-caliber rounds from either a Glock 17, MP5, or shotgun pellets. The Helmet, like the Security vest, is also standard equipment. The armor vest is capable of absorbing and deflecting low-caliber rounds and it protects users from explosives and other types weaponry. An armor vest is standard equipment worn by all Security Guards in Black Mesa.

Half life black guard