AHL STD 67mm Piston Rings for Yamaha TW200 1988-2015 / BW200 1985-1988 High quality nodular cast iron material,corrosion-resistant and durable Effectively sealed gas,improve gas efficiency,to ensure the strong power of engine Scraping excess oil on the cylinder wall to ensure proper lubrication of the cylinder and piston To prevent the piston and the cylinder wall in direct contact,to ensure smooth movement of the piston,reduce friction resistance Quality Assurance!If you are not satisfied with our products,we accept all of the return,replacement or refund requests