... light sensor, vibration sensor, shadow sensor or rocking switch.4.Main component: speaker, PCB, IC, batteries, switch, wires5.Speaker available: 40mm, 29mm ... Battery life: plays message or music more than 500 times8.PCB available: customize size or our existed standard size9.Message available ... down the yellow paperStep 3: stick on the greeting cardStep 4: close the greeting card and re-open, then the ...