de) 1 - Resistor(330 ohm, 1/4 watt) 1 - 9 volt Transistor Radio Battery 1 - Battery Clip to fit Battery 1 - 8 inch piece Red wire 1 - 8 inch piece Black wire 1 - 4 inch piece Black wire tape Completed Tester (battery not shown) If you've purchased the assembled tester all that's necessary is to add the battery clip and battery. There are 4 wire ends that are not connected. 1 red and 1 black are held together by a small piece of clear "spaghetti" tubing. These 2 wires are the tester's "probe" that you will insert into the substance to see how/if it conducts. Make sure these bare ends are kept separate and do not touch each other. Connect the remaining two ends to the wires on the battery clip (red to red and black to black). Snap the battery clip onto the battery and touch the "probe" wires together. The led should light. I have purchased battery clips with the wires connected wrong. If the LED doesn't light, disconnect the battery clip wires from the tester wires and re-connect in reverse (red to black and black to red). Once the tester is working, use