The Rein Porsche Timing Chain Tensioner O-Ring - 99970728840 is a replacement part for Porsche vehicles. It is designed to fit onto the timing chain tensioner, which is responsible for keeping the timing chain in place and maintaining proper tension. This O-ring is made from durable materials and is designed to withstand high temperatures and pressure. It is a crucial component in the engine's timing system and helps to ensure smooth and efficient operation. This O-ring is a genuine OEM part and is specifically designed for use in Porsche vehicles.