ULMER RACING YAMAHA 4 STROKE 4 CYLINDER COPPER EXHAUST GASKETS (Set of 4) These exhaust donuts, machined from Copper, are a replacement for the OEM Graphite donuts used on 4 cylinder Yamaha 4-Stroke snowmobiles. If you're tired of replacing leaky OEM donuts then these may be an option for you. Copper Gaskets replace Yamaha part numbers: 8FA-14623-00-00 8FA-14623-10-00 99999-03989-00 Sold in sets of 4 Fits: 2003-2005 RX 1 (including RX Warrior, RX MTN) 2006-2010 Apex (including GT, RTX, LTX, MTX) 2006-2007 Attak (including GT)