The Geissele Ultra Duty Lower Parts Kit is designed for the most demanding operators and includes all the internal parts needed to complete or rebuild your lower receiver. This top-tier LPK features proprietary Geissele designs, machined with great care at Geissele's facility in North Wales, PA. Key components are made from Stainless Steel, which offers a much longer lifespan and a much lower chance of rusting or failing in extreme conditions or under heavy use.