Exhaust Seal Ring
Each M14-P Cylinder exhaust port uses one of these as the consumable.
Like the other materials which sandwich it ( the Aluminum head Exhaust port and the Stainless Exhaust elbow) this carbon steel donut takes the heat but unlike its neighbors, over time under the extreme conditions of heat its material composition changes and it gets physically smaller. That's why you own an exhaust nut tightening wrench and tap each Exhaust port joint every time the cowling is open.
Want to know if your exhaust donut is finished? Drop a new one on the ground, then do the same to one that has been in service for a while. The new one will have a ring to it, the tired one will sound flat and lifeless.
With the shrinkage of this donut, looseness is created at the exhaust joint, which you should eliminate at the earliest opportunity. There are no winners with engine vibration, and failure to do something about tired donuts can mean this one will start milling away the softer aluminum of your exhaust port - an expensive welding proposition.
After fitting a new donut and re- tightening the exhaust nut, remember to safety wire the nut to the cylinder head.