The Gorilla Machining GLOCK 26,27,33,39 OEM Guide Rod Assembly is a perfect match for a complete drop-in unit made from polymer and stainless springs. providing a lifetime of reliable service. This replacement OEM part is a factory original manufacture piece from Glock. All Factory replacement parts are always manufactured to the exact same print,specifications,tolerances and use the same manufacturing materials as the original parts which guarantee superb fit and reliable fitment. parts may need a qualified gunsmith for installment.