Quicksilver restrictor gasket used on Mercruiser dry joint exhaust engines. Restrictor Dry Joint Gasket | Quicksilver 27-864850A02 Quicksilver restrictor dry joint exhaust gasket For Mercruiser dry joint exhaust applications with one open and one restricted hole Restrictor gasket must be installed on all seawater cooled engines Installed between exhaust manifold and exhaust riser or elbow - see attachment Restricted end must be positioned to the seawater inlet side of the exaust elbow Replaces Mallory 9-61429, Sierra 18-0722 and Barr Marine MC-47-27-864850A02