Vibrating-Pocket Lightprobe

This is a small, pocket-sized (2 1/4" x 1 1/4" x 1/2") lightprobe that can accommodate a key chain or cord. The pulse of the vibration varies with the intensity of the light. It can be used to identify light spots in electronic devices. If placed on a phone panel, it can indicate which lines are being used by detecting the light on the button(s). Battery included.