The product is a set of four DENSO Iridium Power Technology performance alloy spark plugs, model number IK24. These spark plugs have interchange part numbers 958 170 221 90, 101905611G, and 5311Set4. The manufacturer part number is 5311-Set4, and they are designed to provide reliable ignition performance for vehicles. Made by DENSO, a trusted brand in automotive parts, these spark plugs are designed to last and improve the overall efficiency of the ignition system.