Used a few times for toilet training, but my child wouldn't sit on it at all, so I put it away and stored it in a dark place for 2 years. (Wiped with alcohol) ○ As shown in photo 4, there is a black stain, which was present from the time of purchase. ○ The potty seat hook is also included. I believe there are no problems with its function. ○ Being a plastic material, there may be some minor scratches.