- Taking every step, a backapck crushes you with up to 8 times more than it's own weight. - Backpack weight for grade schoolers 3-5Kg, which can harm growth period children's spine. - Climbing with a backpack is one of the reasons of the knee arthritis, especially 7 to 8 times more pressure than backpack weight on the way down. - For usual walking, we take 5,000 steps per hour, 3-to 5 times more presure each step even on flatlands. - This product can reduce the presuure - pressure reduction is maximum 37%. - You can combine this product with your school bag or backpack conveniently. - Patent product.