The 100889107 Copper Flange Gasket is used to provide a ultra-high vacuum (UHV) seal when joining two 4 1/2 inch CF flanges. Copper CF flange gaskets come in sets of 10 individually sealed gaskets and are cleaned and insured to be scratch free. Series 88 flange gaskets are flat gaskets that are placed between two knife edges to provide a vacuum tight seal between the two CF flange faces and secured with flange bolts. Bolts should be tightened diagonally, versus sequentially around the circumference, for a secure vacuum seal. Assembly is cost effective through reuse of components and inch dimensional stubs, sockets, and tubes. The foolproof design provides leak tight joints consistently.