Description Reviews MINI Water Pipe O-Ring 35x3.35mm #11-53-7-548-651 If you're replacing the thermostat and you already have a metal water pipe on your gen 2 MINI, you should also replace the small o-ring (item #2 in the photo) that goes into on the block. It's a small price to pay to do the job right the first time. This is a high quality aftermarket item that is good as the OEM part, but at a lower cost!