Question about Stiebel Eltron ETS 500 Plus

Hello! In the product information, the weight of the appliance does not appear, but it should be 56 kg without the stones and 266 kg with the stones. With the lack of this information, it is not clear whether the stones are already inside the appliance, whether they are included but supplied separately, or whether they are not included and must be purchased separately, as several e-commerce sites propose. In which case what would they be? Stiebel Eltron has 2 different types. Can anyone help me?