When two metal parts are running over each other, you will always have some metal micro parts (metal filings) coming loose. In transmissions, it’s that little left over filings that get absorbed in the oil… Well, this magnetic drain plug will get those micro-metal parts out of your oil and hold onto it for you until your next oil change! I don’t think we have to tell you this is in direct line with the life span of your transmission? Prolong life of your tranny for very little cost!!