Dyrr's Impervious Vestments are a magic item found in Complete Arcane, back when books weren't explicit about which slot items went in.
The first line of the item description calls it a robe, but I see many places on line calling it a vest.
Has it been reprinted anywhere as an explicitly vest slot item? Or are people just reading 'Vestment' and assuming it means 'Vest', not 'Clothing'?