This is approximately 1.8kg of Komei Stone, said to have a lifespan of over 200 years. It's authentic, having cost several tens of thousands of yen. Originally used in a hot spring inn. It is a used item. As a side note, I also use the same stone in a net in my home bath every day. At first, the water may become cloudy when you start using it, but it will eventually become clear. I am not currently considering lowering the price.