Description Solid copper gasket to make a leak tight UHV seal between two conflat flanges. Oxygen free high conductivity (OFHC) copper is normally used as this sealing material as it is very clean, can easily be formed to shape, has a wide temperature range, and has a low outgassing rate. "OFHC" copper gaskets are not always needed for all requirements, we have a range of several different types of gasket materials can be used for most of the general UHV applications. Prime Features > Dimension Tolerance > Outside diameter: +0.0/-0.1 > Inside diameter: +/-0.1 > Thickness: +/- 0.1 > OFHC copper to BS4608 Grade C103, annealed to hardness 80~90 Brinell Welcome to send the inquire to sunwell about this product .