GB300
Open the box carefully and take out yellow case take out the sensor, analyser, battery and cable from tthis. Take the batteries out of their plastic and put then in the analyser, connect the cable and cell. Check the on/off switch works. Then press the button for a few seconds until the count down starts, this is the calibration, when it has finished the analyser should read 20.9. Put a vimed label on the cell and re-seal it, pack all the items back in the yellow box and put a label on the outside then place whole unitl back it to the cardboard box and re-seal. Ensuring there is a bar code on the outside.