ON THE BACK OF THE GLASS FACE THERE ARE 2 GLASS VIALS THAT CONTAIN A LIQUID. THE LIGHT BULBS HEAT THIS LIQUID CAUSING IT TO BUBBLE. WHEN VIEWING THE CLOCK FROM THE FRONT. THERE ARE 2 AREAS WHERE YOU CAN SEE THESE TUBES AND THE FLUID "BUBBLING". THIS IS TO MAKE IT LOOK LIKE THE OIL IS FLOWING THROUGH THE FILTER. 17" DIA. CLOCK RUNS AND LIGHTS AND THE BUBBLING FUNCTION WORKS. NO SHIPPING ON THIS ITEM. AFTER THE AUCTION THE ITEM CAN BE PICKED UP IN HIXTON WISCONSIN BY APPOINTMENT.