For precise measurement of low resistance, capable of measuring resistance from 0.1 micro ohm to 1.1 ohms. Ten standard resistance fo manganin are provided in steps of 0.01 oh each in dia form with five multiply ratio of 0.001, 0.01, 0.1, 1 and 10 ohms. Ther circular slide wire of 0.01 ohms is also made from thick manganin wire having extremely low temperature coefficient. Calibrated to ± 0.05 to 0.02 % with heavy construction.