Jansen AdventureWear is leather armor which may be worn only by Jan Jansen, as long as he has at least 4 Strength and 17 Dexterity. It has an base armor class of 9, which means it doesn't increase the armor class of the wearer and it has an armor class bonus of 5 against missiles. But instead of lowering the chance that Jan can be hit, the armor lowers the damage of all physical attacks with 25%. Jan can cast spells while wearing it. He is wearing this armor when he joins the party. Because he is only available in Baldur's Gate II: Shadows of Amn and Baldur's Gate II: Enhanced Edition as a companion, so is the armor.
This strange armor is made of a foreign material, very supple but strong to the touch. Designed by and for Jan Jansen, only he may wear it. The armor does not give any bonuses to the base armor class, but it does grant a +25% resistance to all physical damage and an additional +5 bonus to Jan's armor class against missile weapons. Jan may also cast spells while wearing this armor. In addition, the armor is stylish.