akro graphite washer

have a duke r. there is a graphite washer between the exhaust just after it exits the rear pot. what is the purpose of this? expansion? mine has disintegrated and needs replacing. have the new one any tips on fitting please. if expansion does clamp need to be murdered up.? or just pinched to allow movement? many thanx

Definitely need to replace i've found that loosening the head pipes as well as the collector for the muffler(s) makes the job easier and the graphite seal last longer.