The Autopilot STK0048 is a Cracked Union Nut Service Kit For Total Control Manifold. Autopilot has been the leading swimming pool salt chlorine generator manufacturer since 1976, offering a full range of units to meet any chlorine need. AutoPilot® can maintain anything from small above ground pools up to very large commercial facilities. This Cracked Union Nut Service Kit is a genuine Autopilot product.