lower the needles onto the test strips and switch on at the main switch ( marked O/I ). ( Note : BK 6 and BK 10 models only. Each switch on the top cover alongside the glass strips operates the pair of needle carriers to which it is closest. Switch on these switches as required.) The needles will now commence their run along the glass strips and automatically stop at the end of their travel, (a few millimeters before the end of the time scale.)