This metal glove protects your hands and lets you deal lethal damage rather than nonlethal damage with unarmed strikes. A strike with a gauntlet is otherwise considered an unarmed attack.
The cost and weight given are for a single gauntlet. Medium and heavy armors (except breastplate) come with gauntlets.
Cost: 2gp, Weight: 1lb
Dmg (S): 1d2, Dmg (M): 1d3, Dmg (L): 1d4, Critical: x2, Bludgeoning
Source: Player's Handbook