Need to insert into the cake 3.5-4cm. 1× birthday candle Size: 13×1.4cm Open the package if the banner up automatically just reset the rubber band on the top back . Light candle after about 7 seconds post wiht rolled-up banner will rise from inside the candle body and banner will roll down. There is a layer of transparent paper on the surface of the candle please do not tear it off. Can test whether it can work normally before lighting the candle .