With an internal mains re-chargeable battery supply the Tinsley 5897 may be used "in the field" for periods of up to 8 hours without requiring recharging. A standard RS232 computer interface is included that may be used for printing resistance values or downloading measurements that have been stored in the instrument's memory. The Tinsley 5897 Portable Micro-Ohmmeter can be used fully auto-ranging or with manual range selection if required. Each of the 6 ranges has a choice of high or low measuring current. Current can be selected to be positive or negative, with the option of automatic reversal to eliminate the effect of thermal E.M.F.'s.