If pressure is applied to 2 lumbar vertebrae at the same time, the inner filling will protrude outward and hernia will appear. The protruding hernia allows us to clearly see the pressure exerted on the spinal nerve. This product is a great product for the patient to quickly and easily understand the problem that the patient will experience due to herniated disc. This model has become 2 times its real size, making it very useful for manual use and group training.