They are from a twin OMC jet drive. They are all aluminum. 1973 vintage and have no leaks. There is no brand name on them. They do not have risers. just the logs. No pictures as of yet. I have yet to learn how to upload pic to the site. The reason I'm selling them is I upgraded my exhaust to Imco Powerflow hedders with 3 inch exhaust hose and tips. The logs were a lot more quiet. I did gain about 300 rpm per engine with the Imco system. Very expensive since I'm running twins. One of the logs had a leak in the water jacket so that is why I'm selling 3 logs. I still have the bad one if anyone wants it as well.