Aim tti micro ohm meter aim tti bs407 p the bs407 is an instrument which is fully optimised for the task of accurate measurement of low resistances with a best resolution of 1 micro ohm br most multimeters offer a best resolution which is at least one thousand poorer than this a very high resolution multimeter may attempt to resolve fairly low resistances but it does so by resolving extremely low voltages typically one nano volt per micro ohm making it subject to severe errors fr