I received this as a gift, so I don't know much about it. ◆ Doesn't scratch the floor. Silent design prevents noise even if the dumbbells collide. ◆ The outer material is made of polyethylene. It won't scratch the floor even if placed directly on it, and it won't make a "clanging" sound when the dumbbells hit each other, so you won't disturb those around you. ◆ The octagonal shape, rather than round, prevents the dumbbells from rolling around, making them extremely easy to use. ◆ The grip uses a resin that fits comfortably in your hand, allowing you to use it without gloves. ◆ Wide expandability and sophisticated design, allowing you to create a barbell using the connecting shaft and adjust the weight. ※ This set includes the shaft, connecting shaft, collars, plates, instruction manual, and training manual. Thank you for viewing.