New O-rings to seal the water cooler. Over time, the O-rings become porous, tear and no longer seal properly. This is followed by loss of cooling water. Original material which is also temperature and glycol resistant. We recommend to replace the rings every time you dismantle them. Manufacturer Information about the manufacturer BAR-TEK BAR-TEK Motorsport GmbH Im Rauschen Auel 3, 51491 Overath-Brombach, Germany info@bar-tek.com