This papercraft is HEV Suit (Hazardous Environment suit, often called the "hazard suit" for the sake of convenience), a full-body hazardous materials suit developed at the Black Mesa Research Facility, designed for Black Mesa scientists to protect them from radiation, energy discharges, blunt-force trauma during the handling of hazardous materials, and the effects of traveling to Xen as part of Survey Teams, based on the Half Life 2 science fiction video game, the paper model was created by Mitchell Montaleone.
It is predominantly worn by Gordon Freeman during much of the Half-Life series - first as the Mark IV suit in Half-Life, then as the upgraded Mark V suit in Half-Life 2. It allows him to sustain many injuries that would normally fatally wound him.
The HEV Suit is related to both the Powered Combat Vest (PCV) used by the Hazardous Environment Combat Unit (HECU), and the armored vest and helmet used by the Black Mesa Security Force. [Source: wikia]