The Elring Oil Line O-Ring - 804380 is a small rubber ring used to seal the connection between an oil line and its corresponding fitting. It is designed to prevent leaks and ensure a secure connection, helping to maintain proper lubrication and functionality of the engine. This O-ring is made by Elring, a reputable manufacturer known for producing high-quality automotive parts. It is a durable and reliable product that is compatible with various oil lines and fittings.