FMF Powercore 4 slip on exhaust muffler part number 045521. This is a new old stock muffler which means it’s been in a dealers inventory a while. This particular one does not have the original box and appears to have been water stained at some point. One rivit is rusted and there’s a film on the muffler. I’d assume that’s just from water and how it reacted to the plastic that covered it for so long. New one retails at $400! BETA RR 350 10,12-14,16-18 BETA RR 390 17-18 BETA RR 400 10-14 BETA RR 430 17-18 BETA RR 450 10-14 BETA RR 480 17-18 BETA RR 498 10-14 BETA RR 520 10-14