Belt of Inertial Barrier gives the wearer of the Belt a +5 bonus to saving throws vs. breath, 25% resistance missiles and a 50% resistance to magical damage (this is not the same as 50% resistance to magic), which makes it a very useful and valuable girdle, and it can be used by all classes, except Kensai and wizard slayers. It has a weight of 2 lbs and it appears in Baldur's Gate II: Shadows of Amn, where it's sold by an unnamed merchant in Trademeet after the genie problem is sorted out.