Is the metal cup sent by Rui Xing insulated?

The metal cup sent by Rui Xing doesn't keep warm. I bought it at Ruixing Tmall flagship store, SF Express, and it was really fast. I bought it for the children. The original cup was too big, and the child needed two hugs. This 300ml is just right. The overall body of the cup is the main color of the small blue cup, and the workmanship in all aspects is more detailed. But as the title, the face value is more than enough, and the performance is insufficient. In other words, the thermal insulation performance is really not good, and it feels below the passing line.