Efficient calorie burning: The waist is relaxing at 360 degrees and is made of soft plastic, so you can exercise without any stress. 10 minutes of use is equivalent to the calories burned after 30 minutes walking. (Hula Hoops) The hula hoop can be adjusted to fit your waist size, so it will not fall out during use. Made of durable ABS material, it is lightweight but still allows you to enjoy the pleasure of slimming without stress. 24 Knots & Freely Adjustable: The hula hoop is made of 24 knots of high-quality plastic, so you can freely adjust the size to fit your body shape and growth, making it suitable for a variety of people. Easy to remove and install, convenient to store and carry, can be used for both outdoor and home use. Easy to use and safe material: The smart hula hoop can be adjusted to fit the size of your waist and twist the waist to shake the gravity ball. It is recommended to use 30 minutes a day to achieve effective fitness while forming the perfect body. The gravity ball is made of high quality and lightweight ABS plastic which can avoid any harm to your body during use.