Hold both ends of the sensor stick to complete the circuit and youre rewarded with flashing lights and high pitched sounds a clear plastic tube thats loaded with red green and blue leds the sensor stick has metallic tape at either end that allows you to complete a circuit and activate the lights and sounds brilliant for sensory play the sensor stick is great for encouraging hand eye co ordinationr r lights and sounds sensor stickclear plastic tube with red green and blue ledshigh pitc