The ball is magnetic (weak), but judging by the weight inside is hollow. The weight is very small 138 grams, so the heat capacity is small. Dry rides without sedimentation. Quality is normal. Does not understand, the body is sealed (the ball does not pull out). For hollow ball, the price is expensive. The seller put a gift, a red thread-mascot on the baby wrist with a miniature wooden fish, my daughter liked, she didn't give me a picture. Taking into account the cool gift and attention of 5 stars.