LED Accelerator Light is used to accelerate the whitening process. Advanced light combined activates the teeth whitening gel to rapidly remove surface stains and penetrates deep to remove embedded residue. please open the battery place and remove the batteries you will find a plastic transparent piece remove it to make the device works for the first time Additional Details ------------------------------ Product description: LED Accelerator Light is used to accelerate the whitening process. Advanced light combined activates the teeth whitening gel to rapidly remove surface stains and penetrates deep to remove embedded residue. please open the battery place and remove the batteries you will find a plastic transparent piece remove it to make the device works for the first time