Material:Plastic Design:may vary according to the stock,customer may not choose. Feature:1.easy to use. 2.Slim your waist week by week until fit.3.For fitness workout,massage and have fun Note:They are light ones,not weighed ones Size:Outer dia.45cm,Inner dia.42.5cm,1.6cm thick Size:Outer dia.45cm,Inner dia.42.5cm,1.6cm thick