POWERED BY WATER. AND IMAGINATION. Gears + oil = a mess. Gears + water = hours of bath time fun.COGS suction to the bath walls and spin when water is poured over them. Positioned just right, they work like a fine-tuned machine. (No oil included or needed!) Use COGS with PIPES or TUBES Bath Toys for maximum fun in the bathtub!Gear heads unite!