high quality stainless steel, as long as its proved after use, i use to wash mine, while hot, dry an then rub with oil and place back onto the still hot hob is enough
also if proving pans you need to be aware of fumes that can come off the oil (to be safe) and off spices if they need cooking off 1st in curry dishes, pepper is a lung crippler when added onto a hot pan, and also chilli
i try an keep nut out of the kitchen when i cook, as i am mildly asmatic, and anything that irritates my lungs i consider an absolute no-no for the nut