Girdle of Frost Giant Strength

Girdle of Frost Giant Strength sets the strength of the wearer to 21. Like all girdles of its kind, it can be worn by nearly all characters and it has a weight of 2 lbs. It's the strongest belt available which boosts strength in Baldur's Gate II: Shadows of Amn]], where it can be gained when fighting the Demon knights which are summoned by offering an animal. It's also required to create Crom Faeyr, a very powerful war hammer. But in Baldur's Gate II: Throne of Bhaal, it's bested by the Girdle of Fire Giant Strength.

In-game description
"Girdle of Frost Giant Strength: This belt is actually the woven hair from a frost giant's beard. When worn the belt greatly increases the wearer's strength making them as strong as a frost giant."