I just did the heat wrap on my exhaust pipe on my xmr 1000 and started to put the exhaust pipe back on and before I got too far I noticed this ring thing on the floor of my shed, thinking what the hell is this, YUP! There are some type of exhaust sealing rings that are recessed into the cyclinder head exhaust port, I never noticed that these fell out when I removed the exhaust but man! Am I glad I found them before I put that exhaust on, just want everyone to know