Graphite Disc Electrodes, Special Grade To Agksp With Ultra 'F Purity, Size - 1/2'' Od X 1/8" Id X 1/5" Thickness, Maximum Allowable Spot Impurities Per Element -1 Ppm And Total Max Allowable Spot Impurities -5 Ppm. Make - Carbon Lorraine (France) Or Carbon (Usa) . ]