Once the Weevil Eye is soldered, test the board's functionality. Put the 20mm coin cell battery into the battery holder, positive side up. If it's dark, you should see the LEDs light up. If not, cover the sensor with your finger to test. If your Weevil's eyes aren't lighting up, don't worry! Start with some simple troubleshooting. Check your solder joints to make sure your components have a good connection to your board - solder should flow into the board and not ball up around the component's pins. Also check to make sure your istor and LEDs are correctly oriented! Colour:As Shown Material:Plastic+PCB Package Contents: 1 * Weevil DIY Kit Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.