Precision-machined guides. Manganese bronze guide material is softer than nickel aluminum bronze valve guides. Excellent heat conductivity which promotes long valve life. Guides can be easily reamed with a battery-operated or electric drill and finished with a high-quality ball hone. Eliminates the need for expensive honing equipment that would be required for nickel bronze valve guides. Machined to accept OEM and aftermarket seals. Made in the U.S.A..
