The Freightliner Socket Headlight Turn Signal is designed specifically for the 3157 Headlight Signal Bulb. This socket is sold individually and does not include the bulb. It is compatible with most Freightliner Cascadia and Columbia models. With its practical design and easy installation, this socket ensures reliable performance for your vehicle's turn signal. Upgrade your headlights with this high-quality socket for enhanced visibility and safety on the road.