Nylon insulated aluminum compression sleeve. Dual rated, color coded end caps. Rated for 600 volts. Provides protection against moisture, extended shelf life and crimpability at sub-zero temperatures. For aluminum to copper or aluminum to aluminum. . Provides for ease of wire size identification (conforms to industry standards) and also prevents dirt and other contaminants from entering the connector prior to use. Holds connector insert in place during installation . Ensures reliability.