JEGS Copper Head Gaskets are made using the most precise manufacturing techniques. Many of the copper head gaskets available today use chemical etching to achieve tolerances. Our gaskets are rolled to their thicknesses. Because this method is more accurate, our gaskets are more consistent and able to provide you with a better seal. JEGS Copper Head Gaskets are CNC machined to the tightest tolerances for ultimate performance and reliability. Designed for use with o-rings in block or head. Reusable. Sold in Pairs. Made in the USA.